There are "dogmatc sedes" which is just another term for anyone who is a devout and consistent Catholic who believes in papal claims (I am one of them).
See, this is precisely the mistake that the dogmatic sedes make, where SV is dogmatically true because of the nature of the papacy (which is dogmatic).
But the dogmatic SVs forget that there are other premises involved.
(over-simplified for clarity)
MAJOR: Pope can't teach error.
MINOR Montini taught error.
CONCLUSION: Montini wasn't pope.
So, because you hold that the MAJOR is dogmatically certain, you falsely conclude that the SV conclusion is dogmatically certain.
Basic principle of logic is that
peiorem partem sequitur conclusio, what I refer to as the logical "weakest link" principle, where a conclusion cannot be more certain than the weakest premise.
Are you dogmatically certain that Montini taught error? You may be morally certain, but you can't be dogmatically certain. Someone might argue a "hermeneutic of continuity". While you may disagree with that, you can't have dogmatic certainty about it ... since only the Church has the authority to teach with dogmatic certainty.
That by itself prevents the SV conclusion from being dogmatically certain.
Or, what if I say that Montini was drugged, locked up in a dungeon, and replaced in public with a double? I may be crazy ... but you cannot say with DOGMATIC certainty that this position is false and that therefore Montini wasn't Pope.
Or what if someone argues that Montini was pope, but he was being blackmailed and his acts were not free and were therefore null and void?
Again, they may be wrong, they may be crazy ... but you can't assert that with dogmatic certainty.
Now what if I distinguish the MAJOR. So, the Pope cannot teach error in teachings that meet the notes of infallibility, but he can teach error in things that do not meet the notes. There's no Catholic theologian who would dispute this. It's possible for a Pope to teach error in matters that do not meet the notes of infallibility. YOU might disagree ... but then "that's like ... your opinion, man" and it's not dogmatically certain, and you won't find a single theologian after Vatican I who believed in absolute papal infallibility.
But then you might argue: "But the Vatican II teachings SHOULD HAVE BEEN protected by infallbility." Maybe, but again, that's like you're opinion, man. And it lacks dogmatic certainty.
Now, it's true that nearly all R&R do reject the SV conclusion precisely by rejecting the MAJOR above. But not all do, and it's not logically necessary to reject it in order to avoid the SV conclusion.
Consequently, the dogmatic SVs exaggerate the theological note of their conclusion.