If you've had to delete 10 posts by the same user, which you suspect is an AI agent, it's safe to say that deleting all posts ever made by that user is a good shortcut.
This was supposed to take 2 weeks of manual work, I took a look at it, googled how to do it automatically, finished the whole thing in a few minutes.
But both this assistant and the PhD they reported to were ready to spend 2 weeks doing it manually.