Can you clarify?
If you agree with those theologians teaching that the pope is unable to teach heresy for the Universal Church, then all the heresies taught since V2 are not heresies at all.
It sounds as if you agree with Fr. Fenton, who agrees with some other theologians of which you speak:
"In this field, God has given the Holy Father a kind of infallibility distinct from the charism of doctrinal infallibility in the strict sense. He has so constructed and ordered the Church that those who follow the directives given to the entire kingdom of God on earth will never be brought into the position of ruining themselves spiritually through this obedience. Our Lord dwells within His Church in such a way that those who obey disciplinary and doctrinal directives of this society can never find themselves displeasing God through their adherence to the teachings and the commands given to the universal Church militant. Hence there can be no valid reason to discountenance even the non-infallible teaching authority of Christ’s vicar on earth".
If this is a teaching of the Church, which it isn't, but if it were, then all trads of whatever persuasion are altogether wrong, because per the above quote it is impossible for a pope to preach heresy.
OTOH, it is because so many wrongfully believe the above to be what the Church teaches, that they've done one of two things, 1) they follow the conciliar popes and are NOers, 2) they are sedes.
For those in my #1, they demonstrate their faith in a [false] Church teaching by following the conciliar popes. For those in my #2, they demonstrate they have zero faith in a [false] Church teaching by their sedeism.
I could spin the same back at you. Is not your faith too some degree dependent on acknowledging that Francis is pope? I mean would you die a martyr's death to uphold that he is?
No, my faith is not dependent to any degree on the status of the pope. I pray daily for him and pray extra for him when I happen across an article or news bit telling of some of the things he does. Beyond that I pay no attention to him. If he were to ever command something, I would do it out of obedience - as long as it wasn't sinful.
And no, I would not die a martyrs death to uphold that he is the pope - that'd be a wasted martyrdom whether he's the pope or not.