Upsetting in which manner? The support of "xx doesn't define a woman" or vice versa?

I think he feels like a prop for someone else's agenda. Imagine living a long life with congenital issues that seriously impacted your physical development, made you infertile etc., then suddenly loads of people are talking about your condition. But it's rarely in order to benefit you, and very often just a sort of debating tactic, to advance the goals of XY people who don't share your condition at all and whose goals you disagree with. I would also find that upsetting.