Semenya's DSD is the very closest to a normally biologically functioning male body in sporting terms as it's possible to get really.
I agree that CAIS, and possibly even PAIS, are irrelevant to the question of transwomen in female sport (although not both necessarily to the question of male DSDs in sport), but if Semenya can compete then any man with male puberty, and fully available testosterone in his body can compete.
Pass CS to run in competition, and Mary, previously-known-as Maurice, can argue to compete without any testosterone suppression or surgical intervention, otherwise it's unfair.
CS is not trans, but CS is a virilised male who competed against females so what's the difference? I'm not surprised that they want to keep a distance from that shit show as it can't help them at all, but there really isn't any logically.