And I thought Ann Barnhardt was their ringleader but, then again, I'm not on the 'inside track' with Bennyvacantism.
No, she's not the ringleader, but did jump on the bandwagon. Antonio Socci is one of the top promoters of the theory. You also have Father Paul Kramer (who used to post here, and with whom I argued a lot). Patrick Madrid of EWTN fame also went Bennyvacantist. I didn't know that this Brother Bugnolo had gone down that path as well.
Basically, Bergoglio finally crossed their "red line" or "line in the sand" in terms of how heretical a pope could be before they came to realize he was no pope. Unfortunately, their analysis is completely wrong, and the heresies did not start with the election of Jorge, and it's only an incredibly native and uninformed person, or someone who's in total denial, who could come to that conclusion. I recall Barnhardt talking about how many people "Traditional Catholics" had "lost the faith" on account of Bergoglio, making no mention of the 100s of millions who left the Church in the wake of V2. That's BS, by the way. No Traditional Catholic lost the faith on account of Jorge.