I think you were right to think that he should have posted a new question. Indeed, if he had not deleted it, I would have rolled back his edit and advised him to post his new problem separately.

I don't think you were right to assume he knows how the site works, even after eight years. Since he doesn't have very much reputation, it could be that he doesn't actually spend a lot of time here. He does, however, spend quite a bit of time at Stack Overflow, and perhaps he knows how that site works. As far as I know, they also would not accept this sort of situation and would expect separate questions. I could be wrong about that, though.