AI probably flagged it or someone made a bogus request. I have seen this happen numerous times, it takes folks having to fight it to get their accounts back. If the person has no strength or interest in fighting it as in this case, then there it goes.
According to Phil's GitLab page, GitHub suspended his account "without warning or reason".
Lucidrains (Phil Wang) GitHub account has been suspended
https://news.ycombinator.com/item?id=47009749