Yes.
I mean, if someone says they are gay, and there's no other way for you to know that someone is gay until they tell you (effectively, self-identify), who in their right mind would 'well actually' that?. As if they somehow know either different or better? You might still want to discriminate against me, or throw me to the ground in response, but what is gained in denying what I call myself?
I mean if someone says he's a gay man and runs around having sex with women all the time of his own volition I think it would be fair to call BS on that.
For a concept to exist there have to be parameters to it. If you're going to say there's no definition to gender beyond what someone calls himself, then that really means there's just no such thing as gender, in which case there'd be no such thing as being transgender as well.
That said, saying ''people who menstruate'' instead to not be noninclusive to the <1% of people who identify as transgender is demeaning to women.
Yeah, for example, I identify as a man, not a "person with a penis", "non-mensurating person" or any other classification social justice activists have invented in the past 15 minutes and are demanding everyone start using. Why is my self identification less important than that of transpeople? It seems like they're the
only ones who get to call themselves what they want and everyone else has to use ever changing jargon that's being made up on the fly to stay out of social justice jail.
If we're really being postmodern about this, someone who says "I'm a man because I have a penis" isn't any more "wrong" than someone who claims to be a certain gender because of a "brain sex". The issue here is not to let people define themselves however they want, it's to impose the concept of the "brain sex" and trans jargon onto everyone else.