Well yeah the physical aspects aren't socially constructed, but "man" and "woman" super are. Nobody who believes gender is a social construct believes that the physical and chemical aspects are, unless they're a ridiculous terf. It's about the way we perceive these things and label them, all of the non-physical aspects of gender, since gender is not physical. Like in Gender Outlaw I think?

I kind of like the "everyone transitioning is intersex" though, that's funny ngl.