What? Yes you can. Observe:
Go fuck yourself, OP.
It's also not like getting banned for petty reasons is anything new. Forum ops, chat admins, moderators, etc all create and control the communities regardless of any corporate entities who own the website as a whole wanting to keep things PG for advertisers. Many of them do so because they themselves got kicked out of somewhere else. If you go into Big Jim's forum and post a bunch of hate about Big Jim, expect Big Jim to ban your ass.