When did America stop being a globalist in the globalization that they themselves created. And how do you justify iran, hoothis, israel, taiwan with an antiglobalist agenda.
In answer to the first question... there's been an isolationist streak among the right for decades. But in answer to the second, expecting consistency from the American right is a bad idea. They do not care about being consistent, any so-called principles are only applied to others -- not themselves. (And I acknowledge that all humans and all groups have the ability to be hypocritical in some circumstances, but it's far more pronounced in the American right.)
As you (probably) imply, the rhetoric is fake and the game continues as it always has. The UNESCO thing is probably a gift to MAGA to distract them from certain other problems/scandals that this administration currently has.
Is it not obvious? Democracies are schizophrenic, where the people and the ruling class are constantly fighting to implement and repeal half-baked bastardizations of their agendas. The best sign that the people have any influence in their government is that there is zero consistent application of anything. Consistency only happens when the democratic element is removed.