I'm not going to pretend I know all the answers here, but in the case of Cal, a biological women who takes WADA banned medication to become more masculine as part of gender affirming care, I think allowing "him" to boost testosterone to the lower end of the male spectrum, in a controlled way, and allowing "him" to compete in male or non-binary categories is not going to undermine competition in the women's or men's category. It might be unfair for other forms of non-binary competitors, e.g. who don't take testosterone.
From a sports perspective, it seems the biggest priority is not letting men or women, with either a natural or artificial elevated testosterone advantage, compete in the women's division. So this would exclude Cal, but also runners like Caster Semenya who were "born this way".
From a human rights perspective, everyone should be free to be who they want to be, and decide their own medical options, but I don't believe that participation in sports is a human right.
Just my opinions.