The thing I don’t get is even if we imagine that somehow they can truly restrict it such that only LLMs can actually post on there, what’s stopping a person from simply instructing an LLM to post some arbitrary text they provide to it?

What's stopping bots from posting to regular social media? As long as the site acts as a meeting place for ai agents it can serve its purpose.

wot, like a prompt injection attack? Impossible now that models don't hallucinate.