There are plenty of rules that we apply across the board. No nuclear weapons for anyone who's not already got them is an example. This doesn't take some spooky one world government to do. This post is wild. Essentially, you're saying that any attempt to regulate AI as the existential threat that it almost certainly is the antichrist. It's bonkers.
That specific rule is enforced by assassinating the leaders and scientists of governments that don't agree to it. See: Iran. I don't think that's what anyone means when they say multilateralism. It's effectively an ad hoc global government defined by the reach of air power.