+Viganò’s rejection of Francis as a legitimate pope is predicated upon an analogy to sacramental theology:

Except that it's not.  This analogy with consent for a Sacrament is an illustration, an example given to help illustrate the point by way of analogy.

I believe my entire post made that pretty clear.

It's universally acknowledged that a man does not become the Pope until he accepts the results of the election.  If he doesn't accept, he's not the Pope.

Nobody is disputing this, least of all me.

So the question comes down to whether there's a difference between material consent and formal consent, the former being "yes, I accept the office" and the latter being "I accept the office as the Church understands it."

This is an invented distinction which does not appear in any of the manuals pertaining to acceptance of the papacy.

I don't believe that defective consent is the "right" explanation for what's happening.  Overall, I try to make a distinction between the fact that Bergoglio is not the pope and various explanations for why he isn't the pope, with the former being far more important than the latter (which can be debated).

Seems like the tail wagging the dog and presuming the premise.

What's key to me is that the Holy Spirit's protection over the papacy precludes a wholesale destruction of the Magisterium, the Mass, canonizations, etc. by legitimate papal authority (as Archbishop Lefebvre himself agreed).  As to how or why they're not the Popes, I consider that something of lesser importance.  I personally hold to the so-called "Siri Theory".

There has been no wholesale destruction of the magisterium, nor could there ever be one.  The SSPX's paper on taking a narrow view of disciplinary infallibility suffices for me.

I'll try to find again the audio of Archbishop Lefebvre, where he "agree(s) with the sedevacantists" regarding the fact that the Holy Spirit would protect the papacy from wrecking the Church, and then speculates a bit about what the explanation for this might be.  He never definitively lands upon one, and that's why he prescinds from fully endorsing the sedevacantist position.

The papacy can never wreck the Church.  The problem is that you say it is already wrecked, so in reality you (and all sedes) are in opposition to Lefebvre on this crucial point.

Just when I thought you may have been coming to your senses, Sean, you're back to this nonsense.

You may have thought your post was clear, but it was not clear to me.  Sometimes that happens when you write something that's clear to you but then it's not clear to others after you make it.

There's no "invented" distinction between formally accepting something and materially accepting it.  Formal / Material distinction applies everywhere, in moral theology, dogmatic theology, etc.  When I have time today, I'll go into how it applies here.

Yes, there has been a corruption of the Magisterium.  When the Magisterium is so bad that Traditional Catholics have to break communion with the putative hierarchy, the line has been crossed, and the SSPX narrow limits of infallibility are total garbage, since they ignore the bigger problem of indefectibility of the Church.

You keep trying to spin away the +Lefebvre audio, and +Lefebvre was not "in opposition" to the sedevacantists on this point.  At the end of the audio, he considered the SV thesis very likely for the reasons stated by myself.  +Lefebvre agreed that there has been a wreckage of the Church to a degree that is inconsistent with the protection of the Holy Spirit over the papacy, and concluded by saying that SV is possible ... based on the same line of argument I present above.

The papacy can never wreck the Church. 

Now we have to define the word 'wreck'?  Anyone attending the Novus Ordo in their local parish?