Did these Ocaml maintainers undergo some special course for dealing with difficult people? They show enormous amounts of maturity and patience. I'd just give the offender Torvalds' treatment and block them from the repo, case closed.
It's clear some people have had their brain broken by the existence of AI. Some maintainers are definitely too nice, and it's infuriating to see their time get wasted by such delusional people.
The AI wrote code which worked, for a problem the submitter had, which had not been solved by any human for a long time, and there is limited human developer time/interest/funding available for solving it.
Dumping a mass of code (and work) onto maintainers without prior discussion is the problem[1]. If they had forked the repo, patched it themselves with that PR and used it personally, would they have a broken brain because of AI? They claim to have read the code, tested the code, they know that other people want the functionality; is wanting to share working code a "broken brain"? If the AI code didn't work - if it was slop - and they wanted the maintainers to fix it, or walk them through every step of asking the AI to fix it - that would be a huge problem, but that didn't happen.
[1] copyrightwashing and attribution is another problem but also not one that's "broken brain by the existence of AI" related.