Considering sex a binary is in fact a social construct. Intersex people exist, “male” seahorses get pregnant. Some frog species can changes sexes to help balance population. A universal biological sex binary is not what nature shows. Claiming such a binary exists is necessarily a social construct, or at least social simplification of reality. Much in the way saying one magnetic pole is positive and the other negative, or “spin” on electrons. They are all social constructs.

The queerness of nature does not care about the mental gymnastics we humans have to jump through to try and make sense of things.