Judging from the last sentence, it seems like you're aware that the word "gender" as it's used nowadays often doesn't refer to biological sex, especially in the context of gender identity/expression. Setting aside the semantic argument, is there even anyone out there saying "there are more than two genders", and actually mean biological sex? What would they even mean by that? From what I can tell, anyone saying "there are only two genders, it's a biological fact" seems to be deliberately shifting the goalposts for the sole purpose of being inflammatory. Otherwise I'm not really sure I understand. I've never heard of anyone saying they were genderfluid as a result of their chromosomes.