If I were a priest, I would not deny the Sacraments to R&R nor sedevacantist nor sedeprivationist, not by reason of their position.  I'm not in any position to impose my conscience on others.  I might have strong opinions on some matters, but that does not mean I have any authority to impose them on anyone else.

How would you handle someone who disagreed with you on the correct interpretation of EENS, instead agreeing with +Lefebvre or the standard trad clergy?  Would you refuse to commune someone who accepted Vatican II but interpreted it through the lens of hermeneutic of continuity? Why or why not?

My response would be the same.  I would give them Communion.  Unfortunately, some of these (what I consider) seriously aberrant, and even objectively heretical, opinions, had become widespread among Catholics before Vatican II, and they were not condemned.  Do I believe that Archbishop Lefebvre's opinion on the EENS issue was objectively heretical?  Yes, I do.  But do I consider +Lefebvre a heretic?  Most certainly not.  If there was anyone who would never knowingly embrace a position he knew to be contrary to Catholic faith, it was Archbishop Lefebvre.  I hold him in the highest regard ... even though I strongly disagree with him on this point.

Here's generally the litmus test for heresy.  If an indisputably legitimate Pope came along and strongly condemned the opinion they now hold, would they refuse to accept the condemnation or would they change their mind?  I am convinced that 95% of Traditional Catholics would accept the teaching and conform to it.  As for who those 5% might be, I am not in a position to judge ... as I have no way to predict which it would be.  So my presumption must be that they're not heretics in the true sense.

That's consistent and makes sense.  

Follow up that may be technically off topic but i'm curious how your reasoning plays into it.  You say you aren't sure if Francis is the Pope or not. If you were a priest would you offer the mass una cuм or not?  Why or why not?

If a certainly-legitimate pope came along and authoritatively condemned my rejection of BoD, then I would immediately drop my position and accept BoD.  Father Feeney said the exact same thing ... for the record.

What if a certainly legitimate pope taught that +Lefebvre was correct on this, in an authoritative manner?  or would you categorically consider that impossible?  

That's consistent and makes sense.  

Follow up that may be technically off topic but i'm curious how your reasoning plays into it.  You say you aren't sure if Francis is the Pope or not. If you were a priest would you offer the mass una cuм or not?  Why or why not?

Not sure.  You might find this funny, but I would offer Mass una cuм famulo tuo papa nostro ... but not insert a name.  This would be a practical expression of my sede-doubtism.  But I would be up in the air on this matter.  Do you resolve the distinction of material papacy without office by inserting the name or not?  I'm not sure.  I believe that people have disagreed on the significance of mentioning the name in the Canon.  

On a personal note, I would certainly have a hard time listing Francis as one of the "cultoribus fidei".  I like to mean what I say.  In that section of the Canon it says, "together with your servant the Pope N. and our bishop N and all the orthodox keepers/preservers of the Catholic and Apostolic faith" (et omnibus orthodoxis atque catholicae et apostolicae fidei cultoribus).  I mean, is Francis really an orthodox custodian/guardian/keeper of the Catholic and Apostolic faith?  I would have a hard time making those words pass through my lips.  I would be cringing every time I said that ... not a good mindset to be in when offering the Holy Sacrifice.

I am not a priest, so I don't have to come to a definitive conclusion.  But, I regularly assist at una cuм Masses and only occasionally go to non una cuм Masses ... as in only once in a blue moon.

Not sure.  You might find this funny, but I would offer Mass una cuм famulo tuo papa nostro ... but not insert a name.  This would be a practical expression of my sede-doubtism.  But I would be up in the air on this matter.  Do you resolve the distinction of material papacy without office by inserting the name or not?  I'm not sure.  I believe that people have disagreed on the significance of mentioning the name in the Canon.  

On a personal note, I would certainly have a hard time listing Francis as one of the "cultoribus fidei".  I like to mean what I say.  In that section of the Canon it says, "together with your servant the Pope N. and our bishop N and all the orthodox keepers/preservers of the Catholic and Apostolic faith" (et omnibus orthodoxis atque catholicae et apostolicae fidei cultoribus).  I mean, is Francis really an orthodox custodian/guardian/keeper of the Catholic and Apostolic faith?  I would have a hard time making those words pass through my lips.  I would be cringing every time I said that ... not a good mindset to be in when offering the Holy Sacrifice.

I am not a priest, so I don't have to come to a definitive conclusion.  But, I regularly assist at una cuм Masses and only occasionally go to non una cuм Masses ... as in only once in a blue moon.

In the Eastern Rite there are some honorifics applied to the Pope that I will also admit subjectively make me cringe sometimes.  I kind of reconcile it by thinking that its more about respecting the office than the particular man, but *shrugs*

Agreed.  For me, if he taught something forcefully to the Universal Church vs. merely opining on the matter, say, in an Allocution.  If he wrote an Encyclical in which he stated that Catholics must uphold Baptism of Desire, I would immediately do so.  Even if the teaching were not infallible in the strict sense, I believe that I am required to give an internal religious assent to the matter.  I believe in the notion of infallible safety as well ... as outlined by Msgr. Fenton.

What if he said that Catholics must hold to Baptism of Desire, and then *defined* that belief in a similar way that its defined by Lefebvre or the SSPV/CMRI?

Right.  I occasionally attend Eastern Rite liturgies as well, and, yes, some of that makes me cringe ... but, yes, the one explanation is that it's the reverence due to the office.  In mean, in theory, the Pope is SUPPOSED to be the chief guardian of orthodox, right?

Right, that's kind of how I take it.  And also since I think he's at least most likely Pope, I want to be praying for him that he wll in fact do those things, even though he currently isn't.  Of course I realize those who don't think he's the Pope would also perhaps pray for him, but it would be somewhat different.  Praying for him to become a Catholic vs praying for a wayward parent to be a good parent.  There's a different relational quality to it (BTW I'm not trying to say the former mindset has zero validity, but its which one you emphasize more.  As I do believe he's the Pope, despite not being 100% certain, I emphasize the "that our wayward parent would actually become a good parent" type of prayer.)