another person's identity cannot invalidate your own. people who believe that's the case have the same thought process as a homophobe does. such as saying, "i'm straight and i don't want gay people around me because i'm not gay"
imagine invalidating an entire group of people because you don't fit into that group
this is the same dumb ideology as, "i'm not non binary, that means i don't want non binary people around me"
well yea because that's essentially calling a trans girl who doesn't want to be called a boy, a boy. but that doesn't mean that people who identify as femboys invalidate the existence of trans women.