Well, first of all, the USA already bombed Iran, so closing the strait is an effect, not a cause.

Second of all, it's also more likely the USA will back down as a result of widespread disapproval, than it is that USA will effectuate a full ground invasion (which would result in heavy losses).

Whereas if they had complied with the don's demand that they be a vassal state of the USA and israel, they would not be a sovereign country anymore.

This isn't exactly abnormal: for a USA analogue, look at Patrick Henry's comments on liberty.