I'm going off of the article, where they state that it's an LLM. It's the paragraph right before the one I originally posted:
According to the former X insider, the company has experimented with AI moderation. And Musk’s latest push into artificial intelligence technology through X.AI, a one-year old startup that’s developed its own large language model, could provide a valuable resource for the team of human moderators.
EDIT: I will include it in the original comment for clarity, for those who don't read the article.