There really should be a law limiting what moderators can and cannot do to the users of their internet forum. I know, I know, it's your site, you own it and make the rules - but the issue of owning the web server is only one side of the coin. An internet forum is not defined by its server, webspace, engine, software, or DNS - it is defined by the set of users who create content by interacting with one another. In this sense, we (Glyphwrights, FretRiders, Leftists, racists and trannies) are the RPGCodex, and rpgcodex.net is merely the access point of our virtual meeting place. And this goes for any other forum. This is the difference between a blog and a forum - a blog is defined primarily by the content created by the owner of the blog - other members' comments are merely an optional addition, I've read a few interesting blogs that were essentially devoid of comments for one reason or the other, and most of them are being updated regularly. A forum who has no posters aside from its owner and staff, however, is an absurdity on the verge of obsolescence. So basically, moderators have absolutely no right to exclude a certain member of the forum from participating in the discussion on the basis of personal feelings, divergent views, disagreements, or private information. This is not your playpen. This is our playpen. You're simply here because you volunteered to sustain this virtual meeting place, and members' donations are your reward.
And yet, most if not all forums maintain a bizarre culture of moderator elitism, indirectly maintaining moderators as "forum nobility" whose actions may not be questioned or challenged (many forums blatantly state "Anyone who questions a moderator's actions will be banned"), who must be respected to a degree far above any "regular" posters, and whose views on a topic may not be disagreed with. RPGCodex is far better than most forums in this respect, of course, but it's not flawless.
The only way to battle the culture of forum totalitarianism and moderator entitlement is by enacting legislation that puts forum moderation under law enforcement scrutiny. When I got stealth-banned at Dragonmount for politely, calmly and rationally explaining that, in my opinion, the Wheel of Time is a horrible fantasy series and that the final volume was an incoherent mess that can be barely called a novel, there had to be a way for me to complain about unfair treatment on part of the Dragonmount administration. You can't ban people for having a different opinion. It's a violation of inalienable human rights. Inalienable, as in, they are in full effect regardless of what you wrote in your forum rules.
entertaining. 
