I don't think Semenya's case is relevant to trans/gender identity, although they are using that to get goodwill and deter questioning. The CS situation is an established type of sports scam (google Dora Ratjen.) Signing up a man or a male intersex person as a female athlete was more common in the "olden days", when doping was less sophisticated and before sex testing became a rule.
Semenya is a very old-fashioned sports cheat, it's almost quaint. It's like the fax machine or the telegraph of sports cheating, where modern doping would be an iPhone. It's not a coincidence that Semenya competed against other athletes like them, they are all doing it on purpose, together with coaches who are likely to be specifically scouting people with this condition.
Semenya is in a difficult position now because their only options are to openly admit that it was a scam or to keep up the charade that they are "a woman" at least part-time, and it's clear which one they're going with so far. I also think, like a previous poster, that there is an amount of grooming involved from their entourage.