So I presume from the comments of a number of you that Francis not a validly elected pope, an imposter, if you will, even an antipope. So the Chair is empty, or presently vacated.  Do I detect a new found respect for the sedevacantist position?

What are they?

"Sedevacantists" is too broad of a category. If we did not know Catholic Knight's position, but we were only told he is a Sedevacantist, how many of us would assume he believes that Pius XII was the last Pope and all the consequences that follow that belief.

Sure, but some sedes say the chair emptied when John XXIII was elected, and others when Paul VI ascended, but nobody (including the sedes themselves) ever disputed both were sedes, presumably because the essential criterion is only that the chair is empty, and when it emptied.

If, therefore, Paul VI sedes are really sedes, why aren’t the Benny’s??

I suppose it is because the "Benny's" are still "R & R" in the they "Recognize" the current hierarchy (Cardinals and Bishops) but "Resist" them. Whereas the classic sedes do not recognize them. They have much more in common with the typical R&R that with the typical Sede.

It never takes long for this kind of a topic to go into the weeds with talk about "sedeprivationists" or 'hard core sedes' who date their position from John XXIII on.  Let's skip all that for the time.  Do any of you, like Fr. James Altman, openly declare that the man presently occupying Peter's Chair is a "fraud" and a "viper?"  Easy question, and should produce and easy answer.