I’m not going to even really try to argue about this but that’s not really true, you could say trans people at stage X of a transition can play in the women’s bracket
The goal is to have women-only spaces, in this case a competitive space. It's essential to filter out men for this purpose, including those who pretend to be women.
Making an exception for the latter if they make some attempt to perform femininity, even if it's a somewhat convincing act, really just undermines the entire point.