> You're talking about making exclusion an intervention, not a result of circumstances.

That's a matter of perspective, a perspective that is the core of this issue. Everything you've said after that is all true if you agree with your priors but people aren't asking you to defend that part, they're asking you to defend your priors, that gender identity is what's important in the segregation of sports and not biological sex.

An enormous part of this discussion has to do with Title IX, generally considered a positive thing among women's rights advocates. It's language deals with sex, the biological term, of male and female (as do many laws).

> No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any education program or activity receiving Federal financial assistance.

Behind all the people on both sides of this argument about what's a man and what's a woman there's the legal issue that it likely (I'm being generous is not saying definitely) violates Title IX to allow males into female sports (in the areas where T9 has authority).

> It would be like banning everyone over 2m from basketball...

This is another framing situation. I'd argue that the better analogy would be weight classes in wrestling. Classes work really well in individual sports to sort people into competitive groups and it works because it's an objective measure.

Unfortunately, team sports like basketball don't have enough players to form a different team for every "height class" so biological females, who tend to be shorter for the majority of the distribution curve, are basically guaranteed excluded by accident of birth. So team sports are segregated by biology because almost an entire sex, 50% of the population, is excluded by the distribution curves of their biology so we now have "sex classes" in most sports to serve the two major distribution curves of humans. Getting rid of sex segregation in basketball and doing so by height instead would make a lot of sense if height was the only factor but there's an equivalent set of distribution curves for things like strength, weight, speed, et al. that it's much simpler to take the thing that those curves have in common, sex, and segregate by them. And back to the previous paragraph, that's why wrestling is still also sex segregated.

I understand that argument and, I think, the sex segregation is a logical solution to the sexual dimorphism of humanity.

I also understand the argument that the social issue of a male/female sexes not being neatly segregated into gender identities, that people generally (also not always) want to segregate themselves, socially, with those people who share a common identity and that includes sports, especially lower levels, that are generally much more social functions than athletic. What I don't see coming from this side of the argument is a defined set of rules that can replace the language of Title IX. Which is totally understandable because gender is exponentially more complicated and diverse than sex. I'm onboard with doing something about this but I've yet to see an understandable replacement for something like Title IX that uses gender over sex.

I have a bit of curiosity about the idea of "identity" being something worthy of segregation considering that gender identity isn't the only type of identity categorization.