I'm not too sure, to be honest.
I'd say it's allowed, but it's at your own risk, meaning OSBot isn't responsible for anything that may occur / we don't directly support the act of gambling.
By default, bans are permanent. Every single ban.
He can feel free to appeal, which he doesn't seem to have done.
Harassing staff is against the rules, so don't do it...
I banned him.
Clearly knew that he was breaking the rules.
He didn't bother even appealing the ban, so no reason for you to do the same, as you already knew what would happen.
Where is your common sense?