My friend was banned without warning for making a moderately angry series of posts on the forums, for which he likely did deserve a warning. However, he did not receive (and still has not received) any formal communication, but was simply banned. No explanation, no chance for apology, and he had already contributed to and would love to continue to contribute to the community in a positive way.
In fact, in one of his posts, he expressed concern that his behavior may be considered warning-worthy, and took care to mention that he is indeed a fan of Stardock/GPG/Demigod and does want to see you guys do great things.
Please don't alienate such an avid fan by banning without warning or explanation, it's lose-lose.