From what I can tell from the moderation log, he was banned for spamming. Since that thread was promoting a game and was in the wrong board to begin with, it's not entirely unjustified. Keep in mind that we get a lot of spam, so do get a bit trigger happy with the ban button sometimes.
This is why it's generally a good idea to demonstrate some willingness to participate in the community when first posting, as simply registering, posting your game, and then bailing is quite common and considered spam according to our rules. That's why we recommend that new users post in the
Introduce Yourself thread first.
In any case, if your friend wants to be part of the community, I'll unban him, but he has to put a bit more effort into participating, and that means reading the forum rules and interacting with other users constructively.
In any case, thanks for reaching out to us about the issue!