At this point it becomes their own choice and it overrides any gender assignment given at birth.
That’s not true. Your gender assignment is defined by how others treat you, how they interact with you, and that’s not completely under the individual’s control. You can’t choose how other people view you, at least not entirely.
That community is on another instance that currently isn’t allowing participation from lemmy.world users. There’s a PC Gaming community on lemmy.world. I don’t know about a general video games community. Someone should start one, because who knows when, or if, that other instance will open back up to lemmy.world users.