> The AIs will soon surpass human capability.

The rule can be revised later.

> I'm worried banning AIs altogether will eventually lead to some form of prove-you-are-human verification to use the site, which will reduce anonymity.

Of all the sites on the Web to worry about this happening, HN is low risk. Oppose that change if it comes, not this one.

> And there is a legitimate use for LLM rewrite to counter identification by stylometry

Source for comment-level stylometry ever actually being someone's downfall, despite availing themselves to every other much more standard defense measure? Regardless, if your experimental means of deanonymizing yourself comes at the expense of the site's quality, it is probably not welcome.