The opening post isn’t complaining about the lack of a non-binary size series, but the existence of men’s and women’s size series.

There is not yet evidence to support your assertion that there is not a non-binary size series on offer (the screenshot provided in the opening post may not be exhaustive).

Even if “the people trying to celebrate this little nugget of gender ideology are conceding that biology doesn’t agree” is literally true, is that really a problem? Much like computer scientists can celebrate the Turing Machine and still acknowledge that one can never exist in reality, why can’t those who celebrate a gender ideology that include non-binary also acknowledge that biology statistically split the human species into two sexes? (“Statistically” because we already know that there are indeed naturally occurring samples that fall outside the two sexes, e.g., those naturally born with XXY chromosomes instead of XX or XY chromosomes, those born with missing or insufficiently developed sexual organs that make traditional sexual classification challenging.)