I think it's a good example though. There is 200 years of medical history to guide us, and anyone trying to use that knowledge before it can be reconfirmed is promptly ejected from the discussion.

Knowledge and correctness are time dependant was my main point. At what point does a theory become a fact? At what point does nuance overrule that previous "fact"?

For these reasons, I can't support any censorship at all.

You don't support any?

What about (from Wikipedia):

Categories of speech that are given lesser or no protection by the First Amendment (and therefore may be restricted) include obscenity, fraud, child pornography, speech integral to illegal conduct, speech that incites imminent lawless action, speech that violates intellectual property law, true threats, and commercial speech such as advertising. Defamation that causes harm to reputation is a tort and also an exception to free speech.