OK, I'll just add an edit to the description, but for you too: the suggestion isn't to force desegregation. It's to allow it. Someone else made a better suggestion: segregate by attributes specific to the sport. In boxing it's weight class, in basketball it could be height, in biking it could even be doped and non doped. Sex and gender need not be the very first thing to segregate by.

Finally, the option to compete together should still be the default, IMO. Some people probably would like to join a mixed team, but simply can't because it isn't allowed. For example if basketball were segregated by height, some shorter players would maybe like to play in the mixed team regardless (maybe they hit a skill ceiling in their league, maybe they don't like the idea of segregation, etc.).