Since you'll undoubtedly ignore that article so that you can persist in distorting His Grace Archbishop Lefebvre's ACTUAL position, allow me ...

Did he frequently and respectfully allude to the sedevacantist explanation of the crisis?

1. “To whatever extent the pope departed from…tradition he would become schismatic, he would breach with the Church. Theologians such as Saint Bellarmine, Cajetan, Cardinal Journet and many others have studied this possibility. So it is not something inconceivable.” (Le Figaro, August 4, 1976)

2. “Heresy, schism, ipso facto excommunication, invalidity of election are so many reasons why a pope might in fact never have been pope or might no longer be one. In this, obviously very exceptional case, the Church would be in a situation similar to that which prevails after the death of a Pontiff.” (Le Figaro, August 4, 1976)

3. “…these recent acts of the Pope and bishops, with protestants, Animists and Jews, are they not an active participation in non-catholic worship as explained by Canon Naz on Canon 1258§1? In which case I cannot see how it is possible to say that the pope is not suspect of heresy, and if he continues, he is a heretic, a public heretic. That is the teaching of the Church.” (Talk, March 30 and April 18, 1986, text published in The Angelus, July 1986)

4. “It seems inconceivable that a successor of Peter could fail in some way to transmit the Truth which he must transmit, for he cannot – without as it were disappearing from the papal line – not transmit what the popes have always transmitted.” (Homily, Ecône, September 18, 1977)

5. “If it happened that the pope was no longer the servant of the truth, he would no longer be pope.” (Homily preached at Lille, August 29, 1976, before a crowd of some 12,000)

Did he consider sedevacantists to be upright members of the Church?

Undoubtedly. He rebuked certain over-zealous Society priests who refused the sacraments to sedevacantists. He collaborated with Bishop de Castro-Mayer after the Brazilian prelate had made his sedevacantism quite clear. He accepted numerous seminarians from sedevacantist families, parishes or groups. He patronised the Le Trévoux “Ordo” with its guide to traditional places of worship throughout the world, which has always included (and still does) certain known sedevacantist Mass centres. He was at all times well aware of the presence of sedevacantists among the Society’s priests.

Did he avow that his persevering recognition of Paul VI and John-Paul II was due more to heroically cautious hesitation than to any solid conviction?

1. “While we are certain that the faith the Church has taught for 20 centuries cannot contain error, we are much further from absolute certitude that the pope is truly pope.” (Le Figaro, August 4, 1976)

2. “It is possible we may be obliged to believe this pope is not pope. For twenty years Mgr de Castro Mayer and I preferred to wait…I think we are waiting for the famous meeting in Assisi, if God allows it.” (Talk, March 30 and April 18, 1986, published in The Angelus, July 1986)

3. “I don’t know if the time has come to say that the pope is a heretic (…) Perhaps after this famous meeting of Assisi, perhaps we must say that the pope is a heretic, is apostate. Now I don’t wish yet to say it formally and solemnly, but it seems at first sight that it is impossible for a pope to be formally and publicly heretical. (…) So it is possible we may be obliged to believe this pope is not pope.” (Talk, March 30 and April 18, 1986, text published in The Angelus, July 1986)

Did he envisage declaring the legal vacancy of the Holy See if the situation continued unchanged?

1. “That is why I beseech Your Eminence to …do everything in your power to get us a Pope, a true Pope, successor of Peter, in line with his predecessors, the firm and watchful guardian of the deposit of faith. The…eighty-year-old cardinals have a strict right to present themselves at the Conclave, and their enforced absence will necessarily raise the question of the validity of the election” (Letter to an unnamed cardinal, August 8, 1978.)

2. “It is impossible for Rome to remain indefinitely outside Tradition. It’s impossible… For the moment they are in rupture with their predecessors. This is impossible. They are no longer in the Catholic Church.” (Retreat Conference, September 4, 1987, Ecône)

By the way, even after +Lefebvre demanded that priests PUBLICLY offer Mass una cuм, he continued to tolerate that they hold sedevacantism as a private opinion.

With regard to the gentleman's post, I agreed with everything he wrote because it wasn't "warped Catholic ecclesiology."  

We'll agree to disagree.

Yep, to put Bergoglio in there next to that phrases is very difficult to swallow.  Latin is "cultores fidei" ... which means more along the lines of keepers/preservers/fosterers of the faith.

Not only is it hard to swallow, it is objectively a lie.  

for arguement sake I say you are schismatic, you have no real defence....the sede position is superior

For myself, it's sufficient to say that I have no need to defend myself against a false accusation, but for argument's sake, my statement did not denouce the pope as pope at all, whereas schismatics refuse all subjection to the pope as they denounce the pope(s) as the visible head of the Church on earth.  

I'm not going to play your game, Ladislaus. If you want an answer from me, first answer my question: I gave you 5 clear proofs from Rome that the SSPX is not in schism.

Xavier, i've responed to multiple of your posts (in this thread and others) and you never reply, so you're not the only one who avoids issues.

Secondly, the new-sspx is not is schism, but new-rome has made it clear that to attend their masses, which are not allowed by the local bishops (because the sspx lacks jurisdiction), are illicit, therefore sinful.  So if you attend an sspx mass, you commit a sin.  You've yet to explain your contradiction here, which is what Ladislaus has pointed out multiple times.  

On the contrary, Trads who attend an sspx mass (or any other Trad mass) do NOT commit a sin of attending an illicit mass because they believe, rightly, that Quo Primum allows any Trad mass to be licit, forever.  Further, they consider this current Church crisis as an emergency situation, per Canon Law, which allows Trads to attend any mass with a valid priest, jurisdiction being supplied by Canon Law itself, whose highest law is the salvation of souls, and this law overrules all other laws.  The emergency situation being the new mass itself and V2 by extension, which sacrilegiously poses as the True Mass and blasphemously ridicules the True Liturgy.

You, however, accept the new mass as only being a "lesser good", instead of the anti-Trent, anti-Catholic, anti-reverent abomination that it is.  If you accept that the new mass is catholic, then there is no emergency situation in the dioceses, then there is no supplied jurisdiction for Trads/sspx, then the sspx has no reason to exist and their activities are GRAVELY illicit, since they directly oppose the authority of their bishops and the pope himself.  If you attend such a mass, knowing their illicit stance, knowing that you have access to multiple masses in your diocese (latin or english), then you sin GRAVELY by supporting ALL their activities, since you are promoting known usurpers of church authority, which is a schismatic mindset, even if not technically a schism (yet...if it continues with no change, it would turn into schism). 

You erroneously believe that you can attend any mass as long as they aren't in schism; this ignores the issue of jurisdiction/licitness and you are wrong to do so.  Now that you are aware of the sspx's illicitness, to attend their masses is to sin gravely.  I hope you please God, follow your conscience, and only attend diocesan masses in the future.  Any other action is hypocritical to the nth degree.

Xavier, i've responed to multiple of your posts (in this thread and others) and you never reply, so you're not the only one who avoids issues.

Secondly, the new-sspx is not is schism, but new-rome has made it clear that to attend their masses, which are not allowed by the local bishops (because the sspx lacks jurisdiction), are illicit, therefore sinful.  So if you attend an sspx mass, you commit a sin.  You've yet to explain your contradiction here, which is what Ladislaus has pointed out multiple times.  

On the contrary, Trads who attend an sspx mass (or any other Trad mass) do NOT commit a sin of attending an illicit mass because they believe, rightly, that Quo Primum allows any Trad mass to be licit, forever.  Further, they consider this current Church crisis as an emergency situation, per Canon Law, which allows Trads to attend any mass with a valid priest, jurisdiction being supplied by Canon Law itself, whose highest law is the salvation of souls, and this law overrules all other laws.  The emergency situation being the new mass itself and V2 by extension, which sacrilegiously poses as the True Mass and blasphemously ridicules the True Liturgy.

You, however, accept the new mass as only being a "lesser good", instead of the anti-Trent, anti-Catholic, anti-reverent abomination that it is.  If you accept that the new mass is catholic, then there is no emergency situation in the dioceses, then there is no supplied jurisdiction for Trads/sspx, then the sspx has no reason to exist and their activities are GRAVELY illicit, since they directly oppose the authority of their bishops and the pope himself.  If you attend such a mass, knowing their illicit stance, knowing that you have access to multiple masses in your diocese (latin or english), then you sin GRAVELY by supporting ALL their activities, since you are promoting known usurpers of church authority, which is a schismatic mindset, even if not technically a schism (yet...if it continues with no change, it would turn into schism).

You erroneously believe that you can attend any mass as long as they aren't in schism; this ignores the issue of jurisdiction/licitness and you are wrong to do so.  Now that you are aware of the sspx's illicitness, to attend their masses is to sin gravely.  I hope you please God, follow your conscience, and only attend diocesan masses in the future.  Any other action is hypocritical to the nth degree.

If Quo Primum allows ANY trad Mass to be licit, forever, then why can't Xavier assist at illicit SSPX Masses under Quo Primum's protection? 

Here are 5 facts about the SSPX neither Pax Vobis nor anyone else touched, You repeat your personal claims about the SSPX, contrary to (1) the Pope who explicitly said to the District Superior in Argentina, "You are Catholic. I will help you." (2) the fact that Priests outside Catholic communion cannot have the power to forgive sins, (3) that SSPX Bishops after the Year of Mercy have ordinary jurisdiction, as Bp. Fellay has confirmed - and ordinary jurisdiction cannot exist outside the Church and (4) that none of 1-3 affects laymen who attend SSPX chapels anyway, but of course you just want that rhetorical point. And I don't need to mention that (5) Come Divine Mercy Sunday, the SSPX will probably have 2 more Bishops with Papal Approval.

Pax Vobis shows a lack of understanding of what vagrant clergy and episcopi vagantes are: https://en.wikipedia.org/wiki/Episcopus_vagans and why the Catholic Church has always held that jurisdiction is not some mere technicality; no, the Catholic Church teaches Orthodox Bishops lack jurisdiction. That's why you can't normally confess to them or their Priests. Auxiliary Bishops are a bit more complex, yet even they have to verify the supply of jurisdiction with the Pope. Purely vagrant ones are not complicated at all. If a bishop is vagans, he needs to be confirmed in the episcopacy and ask jurisdiction from the Pope.

See Fr. Gueranger: "We, then, both priests and people, have a right to know whence our pastors have received their power. From whose hand have they received the keys? If their mission come from the apostolic see, let us honour and obey them, for they are sent to us by Jesus Christ, who has invested them, through Peter, with His own authority. If they claim our obedience without having been sent by the bishop of Rome, we must refuse to receive them, for they are not acknowledged by Christ as His ministers. The holy anointing may have conferred on them the sacred character of the episcopate: it matters not; they must be as aliens to us, for they have not been sent, they are not pastors." https://reginamag.com/saint-peters-chair-at-antioch/ Fr. Gueranger says you should not approach a cleric who is vagans.

I asked Pax Vobis (1) to prove from any traditional, pre-Vatican II source the idea of "material offices", (2) the false teaching of the sedeprivationists that one can continue a parallel sect without jurisdiction apart from the Apostolic Church. He hasn't done so.

Pax also misrepresents some other things. SSPX and Indult Traditional Catholics have every intention to promote the TLM and see it more widely restored; we have full approval and authorization from Rome and the Hierarchy to do so. Therefore, SSPX Masses are not only valid and licit, but will obtain for you abundant efficacious graces to save your souls. They are arguably the best place to be now.

The right approach will bear abundant fruits in the decades to come. Wait and see. You may disagree now, but it will be proven then.

"Simply put, tradition and orthodoxy are not optional. Reverent liturgies, incorporating traditional disciplines such as ad orientem Masses and altar boys serving, aren’t merely a preference. They are foundational. Successful diocese also promote and encourage the Traditional Latin Mass instead of simply tolerating it, or worse, discouraging it. Traditional orders, as example, are booming while struggling dioceses are seeing retirements far outpace ordinations ... Of course, there must always be prayer. Pray for vocations. Parishioners praying from the pews. Young men spending time before the Blessed Sacrament in prayer, listening and discerning. We must humbly ask God for priests. But that prayer, and this is key, must be in conjunction with traditional liturgies and orthodox schools. To pray for priests while rejecting that which forms our young men and assists them to discern, is nothing less than tempting God. We are guilty of presumption." https://liturgyguy.com/2017/07/14/increasing-vocations-isnt-rocket-science/

I get the argument (and I'm not saying I agree or disagree with it, but I can at least follow it) that SVism is schism, but how could it possibly be heresy?

Thanks for the question. To avoid misunderstanding, we could preface the number of years of sede vacante we are talking about. If someone believes in 5 year SVism, I would agree with you that that is probably not heretical; it is schism and wrong, but probably something less than heresy. But what about 61 year svism? What if someone proposed the See of Peter has been vacant the last 100 years? At some point, the person denies the Vatican I Dogma that St. Peter will have Perpetual Successors. My view is that - because of Bishops being appointed and consecrated around 35 and now resigning from office around 75 - 40 to at most 45 years of svism already stretches it to breaking point. Not only will the Cardinals and Roman Clergy appointed by the "last Pope" die or resign, so will the Ordinaries or diocesan Bishops in office. At that time, Apostolic Succession will cease and all episcopal sees throughout the universal Church will fall empty. Would you disagree, ByzCath?

God bless.