“If universal consensus were an indefectibly valid argument for a pope's legitimacy, Clement would have had the right to be considered the true pope, rather than Urban. Antipope Clement was defeated by Urban VI's army in the battle of Marino in 1379 and transferred his See to Avignon, leading to the Western Schism, which lasted thirty-nine years. Thus we see that the universal acceptance argument does not withstand the test of history.”

Presuming Viganò’s history is correct, he has here dealt a severe blow to Billot (and not many are capable of that)!

This is historically correct. Ladislaus can confirm my competency to acknowledge Viganò's claim regarding Urban and Clement.

But then the rationale, based upon an analogy to sacramental theology (which I’m not sure about):

“like a spouse who gets married in church but excludes the specific purposes of marriage from his intention, thus making the marriage null and void precisely due to his lack of consent.”

Nobody says the Church will always adhere universally to a true pope. That is not what the Universal Acceptance argument states. What it states is that the entire Church will never adhere universally to a false pope. As far as I know, the entire Church never adhered to any of the papal claimants during the Great Western Schism, so that event cannot be used as an argument regarding the Universal Acceptance Position.

I think it is uncharitable to call Michael Matt a coward. I think he is anything but that. I would say he is fearless in calling out the criminals undermining the spiritual and temporal edifices. He shames the neo-SSPX. But he's mixed up. His 'unite the clans' crusade is mistaken, based on a false 'tradecuмenism' and doomed to failure. He is not what most of us would consider a 'turetrad'. But he's no coward. I think it is disappointing if it is true that he decided not to let Archbishop Vigano's address go to air at the conference. Such a champion of the resistance deserves to be heard. But we don't know all the circuмstances so let's not get too judgemental.

So up to a point he was not a coward in your opinion.  That doesn't mean he's not a coward now.  Unless he comes up with some good excuse for censoring the sede-leaning comments of Vigano, I'll still say he is absolutely a coward.  Regardless of what you think.  As far as I'm concerned, he responded exactly the way I would expect him to respond.

Archbishop Vigano's argument against universal peaceful acceptance seems to me uncertain, and would not in any case even constitute a common opinion.
His argument on the grounds of Pope Francis's possible lack of consent to the Papacy is nothing more than a thesis.
I don't think this changes anything.
He did state at the very beginning of his address that he was not providing answers, just asking questions that had to be asked.
He also stated near the end that the situation is humanly irremediable.
Yet in spite of that he does seem to be calling for the application of some human remedy, more than just resistance. He clearly wants discussion, seemingly in the hope that it may lead to some solution to the problem which he has more or less said only God can resolve!

I think it is uncharitable to call Michael Matt a coward. I think he is anything but that. I would say he is fearless in calling out the criminals undermining the spiritual and temporal edifices. He shames the neo-SSPX. But he's mixed up. His 'unite the clans' crusade is mistaken, based on a false 'tradecuмenism' and doomed to failure. He is not what most of us would consider a 'turetrad'. But he's no coward. I think it is disappointing if it is true that he decided not to let Archbishop Vigano's address go to air at the conference. Such a champion of the resistance deserves to be heard. But we don't know all the circuмstances so let's not get too judgemental.