99% of this issue is about the validity of calling someone either "he" or "she" when their gender identity is not the same as their biological sex. The use of such "nounself" gender identifiers[0,1] is uncommon and controversial even with the LGBT community[2].
Personally, if I know someone is sincere and wants me to use such a pronoun, I probably would, even though I'd find it odd.
So let's draw the line here: at the very least if someone wants to be called "he" or "she" that should be respected regardless of their biological sex, and agree that it gets "complicated" from there.