Do you get lonely on your mountain?
I cannot see your point that the same “legal theories” (whatever you may mean by that) that allow nude models posing for life drawing classes also cover live sex shows purporting to be academic classes.
Doesn’t work. Laws that used to be enforced against public indecency, obscenity and so on just aren’t enforced any more. Actually in my state, the fiends in the state legislature (actually, I think it was a judge, not the other fiends) decided theaters or whatever they call themselves can legally show live sex on stage.
Live sex shows just are not the same as life drawing classes, legal theory-wise or any other wise.