Being offensive and (knowingly or negligently) false is sufficient for libel against a non-celebrity. Only for celebrities (including public officials, etc.) is it necessary to prove that it wasn't just rhetoric. But I think this fits under "defamation per se" which makes it always count anyway.

I don't know what sufficient for libel means in this context but if you mean that you will win a libel suit if someone because someone engaged in reckless rhetoric against you think again. You are either making shit up or uniformed about the state of libel law. The statement in question seems to clearly be within the "rhetorical hyperbole" exception.

Section 230 only applies immunity within civil law. In some states, libel can be criminal; harassment can be criminal even at the federal level. I am not a lawyer, but I know that investigating this issue could be costly.

Please name the copyright or criminal exception that you think these statements fall under in which Hubski could find its self criminally libel. I can only assume you bring this up to muddy the water, it's baseless as far as the site goes but you don't seem concerned with making arguments that make sense so much as making any argument you can in order to silence people you don't like. If I had a magic wand I would have silenced Grendel, instead I used moderation tools.

Additionally, the offensive user is certainly still liable under civil libel law, which may give Hubski the obligation to reveal his identity during discovery. Is violating anonymity something that Hubski is prepared to do? (Granted, this may still apply even if Hubski does act to take it down, but it is less likely)

There is a whole bunch of legal that would have to happen before this would be an issue, but I'm pretty sure that Hubski would do what they had to. I don't really have a problem with the wheels of justice turning in an appropriate and legal manner. In this specific case the person being slandered doesn't seem to give a damn and the information should have no impact on his daily life as he is protected by his own anonymity. If you have a Hubski example where this could realistically be an issue that would be pursued in an American court bring it on, otherwise keep putting up pro-censorship arguments that have no basis in reality.

Remember that even if a lawsuit is ultimately shown to be unfounded, it can still have significant up-front costs. (This is less true in countries other than the United States, but most other countries do make ISPs clearly responsible for libel that they don't remove once they are informed).

Anyone can sue anyone for just about anything anytime. It's a good argument for censorship like not leaving your house because you could get hit by a car is a good argument for becoming a hermit. Section 230 and various state anti-SLAPP laws offer a great deal of protection for the site. As far as other countries, thanks for more bullshit arguments that have no merit other than to try and install a censorship regime on Hubski. Hubski is in the U.S., American courts have consistently told foreign governments to SUCK IT as far as enforcing their fascist judgments in the U.S. Maybe Hubski's vast European or N. Korean assets could be put at risk but I doubt it.

Finally - absolute domination of free speech is not an ideal goal. Humans are irrational, especially in social circumstances, so the "it is always better to know" theory does not apply. One negative instance can drown out thousands of positive instances; this sort of accusation, even unfounded, can severely effect the ability to apply for a job.

This is why we have defamation law. No reason to make up a bunch of legal mumbo jumbo or tell outright lies in an attempt to frighten Hubski into complying with your version of civility or appropriate discourse. Use the moderation tools or delete your account. Personally I think it's important to not delete things like the Grendel outburst which started this whole thing. It's a maker to be referenced when he seduces his next sad lonely white guy into racist misogyny. Make him own that shit. I'm sure you don't feel that way, you'd rather live in the safe bubble of a child or a European. Stop making up legal bullshit, it's disrespectful and manipulative, anyone who is vaguely acquainted with defamation law can do nothing but think less of you.