Actually, Ginger (fellow PCOS sufferer here), the levels for blood testosterone in women competitors are set to take account of PCOS. IIRC (this is from memory), for women without PCOS, levels are about 1.5nmol per litre. They're about 2.5 for women with PCOS. The upper allowed limit is (was - not sure what it currently is, following the Duttee Chand case) 10nmol. Men typically have levels anywhere between 10 and 30 nmol per litre (so between 4 and 12 times greater than even a woman with PCOS).
The Duttee Chand case was interesting. NB this is to do with being intersex, not trans (no matter how much the trans rights movement tries to coopt and appropriate the medical histories of intersex people, they shouldn't be.) Chand is thought to have complete androgen insensitivity, meaning that although her body produces male levels of testosterone, it lacks the receptors, and so doesn't build male type musculature as a result. She campaigned not to have to take androgen blockers on this basis, and won, I think. The problem was that this then opened the way for other intersex athletes with only partial androgen insensitivity (i.e raised testosterone and the ability to build patterns of musculature which are more typically male) to argue that they shouldn't have to suppress their testosterone levels either. The end result of this was that women who are almost certainly intersex took gold, silver and bronze in last summer's Olympic 800m final.
Now imagine what happens when a transwoman athlete comes along and says "well, so and so who's intersex doesn't have to reduce her testosterone levels, so why should I?" (There is a case already going through the courts in Canada on this basis, brought by a transwoman cyclist). It's basically the end of women's sport.