I'd like to see some supports for this beyond anecdotal one or two cases.

https://www.scientificamerican.com/article/trans-girls-belong-on-girls-sports-teams/

"It turns out that when transgender girls play on girls’ sports teams, cisgender girls can win. In fact, the vast majority of female athletes are cisgender, as are the vast majority of winners. There is no epidemic of transgender girls dominating female sports."

There's also no epidemic of transgender women assaulting cis women in female only spaces.

I'm with Gaiman.