Stubborn - no, the texts would not be relevant to the "una cuм" issue, but to the issue of whether a pope can be a heretic. I think Daly's texts and argument have a lot to say on the issue. Those Galatians 1 and 2 John texts are the ones that I struggle with on the issue not only of the pope but the whole Conciliar Church.
The whole "heretic cannot be pope because it is against Divine Law" error is necessary to maintain a modicuм of validity to the sede doctrine. That's the only reason for it. Maintaining a vacant chair is of paramount importance, we can even say that nothing else really matters. IMO it is only if you can (safely) view this discussion this way will what the sedes say make some type of sense, but still only on the surface.
All sin, every single solitary sin ever committed no matter how small or how terribly bad, is against Divine Law. The sin of heresy is against Divine Law, so is the making of a law against divine law, the sin of stealing is against divine law, the sin of lying is against divine law, etc,.
It is for a very, very good reason that the popes made it a law that the one elected, even if a heretic, is instantly pope upon his acceptance of the election. But the sedes absolutely and positively must reject this law - which, according to their own thinking, is a sin - against Divine Law.
Add to that, the popes who made the law, are ipso facto guilty of sinning against Divine Law. Which of course leads to a conclusion they completely ignore, i.e. those popes lost their office by making a law against Divine Law.
2 John says the same as Galatians, he says to not listen to "an angel from heaven" and to "let him be anathema." Why didn't St. Paul say "do not listen to him because he's not an angel from heaven?" Or "it will not be a false Gospel if he really is an angel from heaven?"
Because the only thing that matters is to not listen to false Gospels, to not listen to lies wherever they come from, we are to flee the danger, not try to decide if he's really an angel - because whether he is or is not an angel from heaven does not matter one iota, it most certainly did not matter to St. Paul and it most certainly does not matter to anyone else. The only thing that matters is to not listen. That is what that Scripture is teaching. That's why St. Paul said what he said and did not elaborate on the [im]possibility of it all, or the [il]legitimacy of the "angel from heaven".
Consider that instead of fleeing, we go contrary to that Scripture and hang around and decide he really is an angel, the danger in that is that we will listen and believe a false Gospel - because we did not flee and did not "let him be anathema." Now for the heck of it, let's say that the angel is the pope - what matters is that we do not listen - without any consideration whatsoever to his [il]legitimacy. This is what St. Paul taught us to do - and as always, for very good reason.