My friends account was banned, I'm guessing it's permaban as it did not state how long till he can post again.
My friend did not receive any warnings at all or any temp ban.
So I'm wondering what are the grounds for permaban without warning?
I think it will be permanently ban. Your friend get ban because they didn't follow the rules or your friends post is just copied from other user. Not following rules may get punished nor perma ban.