Trans individuals have a body with one set of 'plumbing' and a mind which says to them clearly that it's the wrong plumbing. If sport were entirely mental, perhaps it would be no problem, as for example in chess or bridge. Athletic sport is far from entirely mental, I hope we can agree.
The reason sports are divided by gender is that evolution has dealt the two sexes different physiological capabilities, particularly at the extremes where highly trained athletes operate. An athlete with a male body whose mind tells them they are female still operates with a male body. They do so unfairly, in my view, if they compete with biological women.
I've not read of any trans "men" winning athletic competitions against male athletes, have you? Do you expect to see many such? I don't.
I've not read of any trans "men" winning athletic competitions against male athletes, have you? Do you expect to see many such? I don't.