The problem is male prisoners, yes. Which is why segregating prisoners by sex is an essential component of safeguarding. And then further separation of vulnerable prisoners within each prison. If, in a male prison, there are inmates who desire to be women and are deemed to be at risk based on this, they should be separated from the general prison population, like other vulnerable prisoners are. Not transferred to a female prison.

Regarding the female category of sports, a sample of cells taken via a cheek swab can be used for karyotype testing, which would be sufficient for screening female athletes. This is much less intrusive than the anti-doping tests - which involve having blood taken and being observed urinating - that for many athletes is a requirement to compete. In the unusual case that the athlete has something other than 46,XX sex chromosomes, further analysis could be done - with the athlete's permission - to understand the underlying condition and, from this, determine eligibility to compete in this category.

No-one is advocating for all female athletes, including children, to undergo genital inspections. It isn't necessary and it's not being asked for.