The author is really reaching here.

Defines everything as male or female, then wants to argue that everyone is unique or something... this is pretty trivial truth stuff.

Nobody conforms in reality to any gender ideal, but the ideal of trying do is what motivates a lot of people's social behaviors and expectations for themselves and others. That's why they are ideals. Also why gender identity is so fraught with conflict, because everyone is chasing after some ideal and demanding others do the same as them, often in the context of making themselves sexually appealing.

Biology doesn't have ideals, just traits. And the traits that matter are those that allow you to reproduce. and yeah, in some cultures being more androgynous would be advantageous, in others, not so much. it's all variable.

none of this disputes the fact the vast majority of human beings are male or female biologically. and there a subset that are not.

I will never understand this weird fascination that there has to be two sexes absolutely, or none at all. There are two sexes for the vast majority of species, but not all. Some species can change sex, some can't, some are hermaphrodites, some can produce asexually and sexually, etc.