[Dimond] doesn't actually touch on whether or not these men are Catholic (or popes).
That is correct, and that is why I find his presentation useful.
I think I know what Siscoe is trying to do. He is going after the First (and true) Premise of SV: They Ain't Catholic.
Like the SV's he tries to rebut, he is looking for logical closure. He possibly thinks that he cannot reach logical closure (except SV) if he admits the truth of the First Premise. Wherefore he seeks to falsify it in order to avoid having to arrive at the SV conclusion.
Dimond is sticking in this presentation to the defense of the truth of the First Premise, and I'm very happy he is doing that, because the truth of the First Premise of SV is what is hotly (and erroneously) denied by R&R. Their denial of this truth is what produces all of their bad fruits.
NOTE: This denial is sometimes explicit, and quite often implicit.
I am not promoting Dimond's presentation as the answer to any ultimate question. As I said, he is providing quite a lot of food for thought. I want to hear all arguments for the truth of the First Premise.
Siscoe is trying to come up with a reasoned analysis that falsifies the Premise. He has put forth more effort than many R&R proponents, who do more sidestepping. I commend him for trying, but he is not even remotely convincing. I agree with Dimond that he is blowing a lot of hot air. I also suspect that Dimond is right in calling out his argument as one that is novel and not backed up by Magisterial teaching authority.
Food for thought is what Tradition sorely needs, because Tradition has bogged itself down into two unsatisfactory positions that seem, at this late hour, to exist, not for the propagation and defense of the Faith, but solely to contradict one another.
Tradition has stopped multiplying. It is now in a terrible state of division, corruption, disrepair, and contraction. I hold that the sorry state of the Catholic counter-revolution is due entirely to endless artificial and sophistical posturing, at the expense of the propagation and defense of the integral Catholic Faith.
Neither SV nor R&R has been able to pull the Church out of Her tailspin. By their fruits we see that God is not happy with our current modes of operation.
I'm going to continue going through Dimond's presentation because I think he frames some excellent questions.
Thanks for your responses, Mith!