Twisting words once more. Sedevacantism comes from the acceptance of the reality of the situation based upon Catholic teachings. A heretic cannot be the Pope, nor can an apostate; you've already admitted that these "Popes" are heretics, and since there is no known claimant to the Chair, then the Chair must be empty or the Church has defected and the gates of hell have prevailed. Since the latter is absolutely impossible, then the See is vacant.
You were already shown that the popes since at least Pius X made it a law that heretic cardinals were to partake in papal elections and on that account could be elected pope. This means you only base this assertion on only your opinion, not Catholic teaching. This truth will remain no matter how often you repeat the same error.
What does Pope Boniface's declaration have to do with this? All baptized are automatically subject to the Roman Pontiff. That doesn't prove that Francis and his predecessors are legitimate Pontiffs at all. And my position doesn't reject that dogma anyway because I would absolutely be subject to him if there were a Pope.
It is rather remarkable imo, how there is some over-riding mental block in sedes that make them fail to acknowledge the obvious fact that the bolded opinion / statement they all make, changes the meaning of sacred dogma to this:
"Furthermore, we declare, we proclaim, we define that it is absolutely necessary for salvation that every human creature be subject to the Roman Pontiff unless you do not believe he is the pope."
You honestly do not see this as changing the meaning into something that means absolutely nothing at all?