However, this does suggest, if we accept it, that it is not always chromosomes that would be the final line. If we found [CAIS athletes] weren't over represented, or were under-represented, would we say that it was logical to class them as women for sporting purposes?
From the NHS website:
AIS is caused by a genetic alteration that is passed along the female line to the child.
Although people with AIS have XY (usual male pattern) chromosomes, the body does not respond to testosterone (the sex hormone) fully or at all. This prevents the sex development of a typical male.
Normal male sex chromosomes, lack of response to testosterone.
The fact that they are over represented on podiums was the proof of the advantage gained by (we assume) not having periods and being on average taller. The advantage will not change, nor will the source of it - being male. So even if they stop being over-represented on podiums, it would not mean that they had no longer had any advantage on average, or that they were no longer male, because they could be falling away for any number of reasons.
Men as a class are excluded from female competition because of male advantage - the advantage they have over women y virtue of being male. One particular group of males not having an advantage (although this particular group always will) does not justify making an exception for that one group.
Don't be mesmerised by the fact that CAIS males have a phenotype which closely resembles the female. Looking like a woman is not what makes you eligible for the female category. Being female is. CAIS males do not have female internal anatomy. The resemblance to women is purely external. They are always going to have an advantage for the reasons I've mentioned before - height and lack of periods. This is not going to change.
Jonnie Peacock's T44 Paralympic 100m times were comparable with women's times. JP would also have had male advantage, but greatly reduced by the fact that he had 1.75 legs instead of the full complement. We didn't therefore allow Jonnie Peacock into the female category. He and any CAIS athlete still belong to the class of males, not the class of females.
A CAIS athlete is just as male as Usain Bolt. They are weaker and slower than Usain Bolt. So are women, the argument runs, therefore it's reasonable to let the weakened males race with the women. It's not reasonable. The argument for allowing CAIS males into female competition is exactly the same as the argument for allowing any male in.
(It does raise some interesting questions about suppression of menstruation through drugs, whether that also is an unfair advantage by using drugs, because it's quite common now among female athletes. How far can we play with our biology before it's not fair? Does it create a situation where all elite female athletes feel obliged to do it to compete? Is that healthy?)
It may be an advantage, but it's not unfair because all of the competitors could suppress menstruation if they chose. (A male would not have to.)
I am curious to know why you are so invested in allowing this group of males into the female category, though. Obviously, we are different people, but to me it seems blindingly obvious that males should compete against males and females against females. And since everyone is either male or female, there's no need to make exceptions.
There is no corresponding opportunity for a woman to compete in men's events. Especially not a woman weakened by a DSD or other medical condition. So the inclusion would only go one way. In sport terms, males have the equivalent of a vast stately home with deer park and landscaped gardens, while women have the gatekeeper's cottage and a small kitchen garden. You are suggesting that we might give up some of our garden and a room in the cottage to male people, and I am simply trying to understand what is driving your take on this.