There is no moral equivalence between the requirement of every Catholic to distance from things not Catholic, and the decision about whether claimant X or Y is actually the Pope.
Nobody is going to hell one way or another for that decision. You are certainly sinning though when you say it is the same thing as separating from heresy .
I never said you were going to hell for getting the identification wrong. That's a straw man. The issue goes way beyond mistaken identification or getting a test question wrong.
Why don't you understand that for most Catholics the Pope is their rule of faith. Most don't know their faith very well. So they look to the Pope as their guide. Not to Tom and his merry band of 20-somethings.
If you tell them that heretic Bob is the Pope you are scandalizing those people, and many will simply follow heretic Bob into their own destruction (mortal sin). They will not join your little band of Resistors.
The false Pope knows human nature. He knows if he suggests, like the serpent did to Eve, that certain behaviors are A-OK in God's eyes, then most Catholics will take the bait. He'll say, "Surely you aren't going to die (spiritually) if you sterilize yourself. Come on. Jesus is a kool dood. Long hair and sandals, bro. He gets us. Be fruitful and multiply...but do it responsibly."
That is the danger you do not understand. If Tom simply ignores the Pope but spends every waking moment bashing Sedes, people will think Tom is just weird. But Tom just confirmed for them that heretic Bob is "the Pope." Most sane Catholics understand that you do not ignore a true Pope. They will not ignore him. It is prophesied. And you are not helping them understand why they must ignore him.
They must ignore him because he is an agent of Satan. He will lead them astray. He is a pied piper. Calling him "the Pope" or "the Holy Father" is anti-evangelization.