Spirit, while I'm all for a more laissez faire approach to moderating (in all the forums I've moderated or administered I've banned one person, for linking to g0at5e), don't try to rely on the First Amendment. I see people invoke the First Amendment all the time on forums, and it's a bit of a pet peeve.
It gaurantees free speech in public places, but it doesn't mean I'm going to let someone into my home to say whatever he wants. On a private forum, one has the rights given to him by the admins. If one is unhappy with said limitations, the standard solution is to go elsewhere.