Yes, but my point isn't only the above. It's also that you note that Stock grants that exceptions exist. But rather than pushing back only on Stock's repeated attempts to forget that she already granted exceptions, you try to undermine a well-established model that nicely captures the dominant systematic biological variation.

You don't even manage to make your own case convincingly. You say "there are also many examples of cultures that draw sex/gender boundaries in an altogether different way", and give two examples...which...draw the boundaries exactly the same way for the overwhelming majority of people. The Talmud can't even talk about the bigender/agender categories cleanly because there's no neutral pronoun in Hebrew! The "unary lack of distinction" example shows no such thing at all--the usual anatomical/biological distinction is made but the point is that it carried comparatively little weight in terms of organizing society. (It carried more than zero weight. For instance, women went to live with their husband's family rather than vice versa. I really do not understand the claims made by the author of that piece arguing that gender was irrelevant while in the middle of giving examples of how it was relevant. It seems like motivated reasoning of such high order than I am forced to question every characterization made there.)

And this is because, in fact, people do tend to use language to cleave nature at its joints, when a joint is evident, and the male/female distinction is a very evident one.

When we have abundant surplus capacity, it hardly matters. But when we're challenged, even something as simple as the number of syllables can make a difference (albeit with some weird quirks: https://pubmed.ncbi.nlm.nih.gov/21506452/).

What was the point of linking to clustering algorithms if not to admit that we love to be able to stick labels on things with similar characteristics?

You say, "The reification of sex *as* gender, i.e. the idea that there are two classes that you can be born into, and that which one you're in governs your nature, is where Stock moves onto from this." But it doesn't mean that the original male/female dichotomy (+ exceptions that she admits) is wrong. You make a convincing argument in many other places by attacking the flawed premise. But here you're attacking a completely okay premise that is used badly. Attack the usage!

There's nothing wrong with saying, "Okay, great! We have now established that there are men and women by observing and naming a pronounced if multi-faceted regularity. But we're not talking about the ordinary case here, are we? So let's investigate other regularities, and maybe name them so we don't just pretend they never existed even though they were admitted earlier."