Hate speech, discriminatory speech and defamation, lots of speech is criminal. It depends on context and intent, for which misguided tolerance for bullying we're now witnessing. For especially bad cults, ie. Germany banned Nazi symbols and speech.
Policy is made in a context, not just blind ideology.
If they know of criminal conduct, they might be liable for not reporting or supporting such activities. There's also bad PR and various guilt-by association. Take a hard look what happened to the founder of Wikileaks for instance.
Policy is made in a context, not just blind ideology.