I don't know really anything about XSem, including his age.  If he knows little or nothing about ABl or de Castro Mayer, that is something he will either have to confirm or deny.  It would behoove him, however, to know something about the close relationship between the two bishops.  What I wrote above is absolutely true, as reported by +W himself.  Bp.de Castro Mayer did far more than just consider the possibility of the SV position.  He was poised to embrace it totally, and he may have done so before the end of his life.

“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)

As it is now the sedes are treated as second class citizens in the greater traditional Catholic community.

Agreed. In that speech, +ABL is attacking the folly of trying to preserve Catholic Tradition without Catholic Bishops chosen from within Tradition - it is almost a logical impossibility. In the General Chapter of 2012, if you note, there are 6 conditions. Here's a conference of His Excellency Bishop Alfonso de Galaretta on the first 3: https://rorate-caeli.blogspot.com/2012/10/from-dici-sspx-rome-present-day.html

The first:  “The freedom to keep, transmit and teach the sacred doctrine of the constant Magisterium of the Church and of the unchangeable Truth of divine Tradition”.

Next, the second point:  “To use the 1962 liturgy exclusively”, and therefore the whole liturgy of 1962, not just the Mass:  everything, even the Pontifical.  To preserve the sacramental practice that we have presently, including what concerns Holy Orders, Confirmation and Matrimony.

Then, still within the sine qua non conditions:  the guarantee of at least one bishop."

All of these were arrived at after very careful study of +ABL's whole life, letters, actions and teaching. Bishop Fellay said something like, "When we study +ABL's words at the time, we conclude he would have accepted what is now being proposed". If +ABL would not have accepted even when Bishops were granted, right to teach Truth and condemn errors, and offer the True Mass and Traditional Sacraments exclusively were acknowledged, why did +ABL say all those other things all those years, and even imply that, with Bishops guaranteed and other sufficient conditions, even the 1988 protocol would be acceptable? If even in 1990, +ABL can say, "For what has been up till now the difficulty has been precisely their giving to us a Traditionalist bishop. They did not want to. It had to be a bishop according to the profile laid down by the Holy See."Profile". You see what that means! Impossible. They knew very well that by giving us a traditional bishop they would be setting up a Traditionalist citadel able to continue" it is obvious to us +ABL would have agreed with us.

Anyway, for this thread, here's one of three other letters. All 3 can be read here: http://www.sspxasia.com/Docuмents/Archbishop-Lefebvre/Apologia/Vol_two/Chapter_41.htm

"Letter of Mgr. Lefebvre to the Sovereign Pontiff¹
Most Holy Father,
To put an end to some rumours which are now spreading both in Rome and certain traditionalist circles in Europe, and even in America, concerning my attitude and my way of thinking with respect to the Pope, the Council, and the Novus Ordo Mass, and fearing lest these rumours should reach Your Holiness, I may make so bold as to reaffirm my consistent position.
1. I have no reservation whatsoever concerning the legitimacy and validity of your election, and consequently I cannot tolerate there not being addressed to God the prayers prescribed by Holy Church for Your Holiness. I have already had to act with severity, and continue to do so, with regard to some seminarians and priests who have allowed themselves to be influenced by certain clerics who do not belong to the Society.
2. I am fully in agreement with the judgment that Your Holiness gave on the Second Vatican Council, on 6 November 1978, at a meeting of the Sacred College: "that the Council must be understood in the light of the whole of holy Tradition, and on the basis of the unvarying Magisterium of Holy Mother Church."
3. As for the Novus Ordo Mass, despite the reservations which must be shown in its respect, I have never affirmed that it is in itself invalid or heretical.
I would be grateful to God and to Your Holiness if these clear declarations could hasten the free use of the traditional liturgy, and the recognition of the Society of St. Pius X by the Church, and likewise of all those who, subscribing to these declarations, have striven to save the Church by perpetuating its Tradition.
I beg Your Holiness to accept my profound and filial respect in Christo et Maria.

†Marcel Lefebvre"
The SSPX doesn't accept the idea that all these letters and everything +ABL wrote before some particular date is suddenly invalid.
God bless.