You believe China and Europe would go to fight with US instead of Iran, if/when we get to a point of actually hurting enough to join that fight?
I don't see that happening... Also if they want to escort tankers, they can escort tankers from US-allied countries, and I assume US would also help.
Overall, I legit do not see a way where countries would pick to fight against US instead of Iran if we ever get there. But maybe, I am wrong, so who knows :)