It's not about cosmetics or feelings though, it's about anatomy and physiology.
Someone like Eden Atwood is indeed unambiguously female, unless you pull out a DNA test or ultrasound screening to check internal organs.
I don't think a CAIS person is going to have male-typical muscle tissue, heart size, lung capacity, etc. since they go through female puberty sans menstruation.
I wonder if there's ever actually been a top athlete who's XY/CAIS. It would be an extraordinary coincidence, since top athletes are a tiny fraction of society, and XY/CAIS people are also a tiny fraction of society, and from my understanding there's nothing about being XY/CAIS that would give the person an edge over women such that they would be any more likely than a random woman to become a top athlete.
> And it's still blatantly sexist to label everyone as either "male" or "non-male" and dump intersex men into women's categories due to their lack of traditional male genitals.
I don't think it's sexist to say that a person can be considered a woman if they were born with female external anatomy, such that everybody assumed they were simply a normal girl, and thus they were subjected to all the same treatment other girls are.
Even if they learn in their teens that they're genetically male, it's unlikely to change people's treatment of them much, especially since most people who encounter them in daily life won't know anyway.
In terms of how society views and treats them there's barely a difference between them and a woman who happens to be infertile due to some other issue.