If sport became non gender segregated, fewer females would participate. We have volumes of data to support this.
When girls look around and see females that they do not identify with and do not understand and instead are presented with a narrative which says if they are more GI Joe than Barbie, then they are trans, if they do not feel comfortable in their emerging female body, that that be fixed by binding, top surgery and puberty blockers, if they do not like how women are treated by men, they can disguise their female nature. If they are male but wish to experience what it is to be female, they can identify into female spaces and coerce everyone in that space to accept them or risk being themselves excluded from that space if they prefer not to affirm this fiction.
This narrative is more harmful to women and girls than it could ever be to men. Women are told that they are wrong to fear this but their fears are not explored or recognised. We have had millenia of our feelings being ignored... and this latest narrative reinforces our oppression.
I spent my teen years and twenties believing that we had reframed gender stereotypes and we could have it all and then my thirties and forties seeing the realities as men progressed while women stalled, despite railing against it, finding myself in the company of other educated women, achieving less than their potential, putting the needs of others before themselves, being asked to organise the Christmas party, being chosen after less highly performing men, fighting for space in the gym, seeing the ingrained structural inequalities in the lives of our daughters. This is not because women don't try hard enough, are not good enough or because they choose not to, it is because our society is structurally unequal. Fighting for equality for women from a privileged position of being white and middle class does not make my fight less valid. When the arguments for inclusion are built on the arguments for sexual equality, reformulated and presented back to me as arguments for trans inclusion and painting me as a bigot.. I struggle... I really do... but until women have equal share of power and money in the world, we should not give ground. We can encourage acceptance of other people's right to present as they wish but should never accept the redefinition of what a woman is. It is the fact that we are women, that we are oppressed, taking away that definition will not remove our oppression. Fighting to keep the definition is not synonymous with fighting to retain our oppression. It will not liberate us, it will further oppress us.
I know I am preaching to the choir.. the OP could have read these opinions 100 times over on this site ..... but obviously remains unconvinced.