I don’t think the definition of dogmatic fact was ever intended to apply to men who cast doubt on their own legitimacy. When tens of thousands of Catholics are having doubts about the legitimacy of the Conciliar popes, it is already long past the window of applicability for that particular doctrine. And it’s not just a few cranky laymen. Hundreds of clergy are having doubts too if they haven’t already come to the conclusion that the see is empty.
In another thread, I offered as a possible explanation the post that the pre-conciliar popes were dogmatic facts, but the conciliar popes were not, because these latter were suspect of heresy.
But that’s just me trying to make sense of how Lefebvre could have countenanced the possibility of sedevacantism, in light of the teaching of Billot which he himself quoted on another occasion, making the universal consent argument.
But I am not sure that I can find any theologians making the same argument.
To be honest, I think I would be more inclined to accept the common teaching of the pre-conciliar over a contrary Lefebvre (preferring to believe the latter sometimes said things in the heat of the moment which ran contrary to his more common teachings/positions, as Michael Davies said the Archbishop admitted to doing in Apologia (Vol. II, Ch. 40).
Obviously, I could be off base here, and am still trying to make sense of all this .