Moderation is a form of censorship. The Codex is probably a bit extreme in some ways, but its lack of censorship promotes the stimulation of ideas and debate that could never take place, for instance, on this forum. Do I care to read all of the debate? No way. Still, it's leaps and bounds above many places for this reason alone. *cough* TESF *cough*
Not to mention, in the cloud of shenanigans at the Codex, there are serious discussions that take place. While some people will troll you, discussion is rarely hinder by such people simply because the norm of posters are used to such tactics. It's an example of things simply running there course.
As for the porn links and over the top racism, from time to time, it can definitely be a drag, but these posters are merely a loud minority.
In terms of the idea of censorship, many forums will fall pray to dissonance of facts and confirmation bias. Moderation, especially over moderation, is the segway for such problems. There has to be dissonance, troll tactics, and rhetoric that is above and beyond. Without these things, one cannot form an accurate opinion about the weight of what someone says. For example, people who post in such ways carry less weight with their message. The Codex understands this.
And yes, I was lurking and followed a link. Hello ;P