If it's only a matter of hormone levels, and by your standards this situation is fine because his testosterone levels dropped below a certain threshold, why aren't seeing the same situation happening in men's sports? Ie, transgender man supplementing testosterone and competing in the NFL, NBA, etc.? 

The best female basketball player in the world would not make an NBA practice squad. The fastest 100m female sprinter in the world wouldn't qualify for trials. Are you asserting that would change with, say, a year of test supplements for a female...er transgender male? Of course it wouldn't.