Earlier quoted context omitted.
Are you sure about that? I am usually a pretty strong free speech advocate, up to toeing the line of being a free speech absolutist at some points in my life (of the: "nuclear weapon blueprints posted online are just as valid speech as any other sequence of bits, information wants to be free!" variety). But I still think you can design speech codes that are not prone to slippery slope under any sane interpretation. I…
> fighting words This isn't an exception to free speech protections. 'In 1942 the Supreme Court held that the government could prohibit "fighting words" — "those which by their very utterance inflict injury or tend to incite an immediate breach of the peace." The Supreme Court has been retreating from that pronouncement ever since. [...] the only remaining focus is on whether the speech will provoke immediate face-to…
But, ok, if you want another U.S.-based exception: some information regarding nuclear weapons is considered to be 'born classified' in the sense that even if you develop it on your own without clearance or access to classified materials, you still are not allowed to divulge it. That is another government-enforced restriction to free speech, although admittedly a sensible one on the justification of the survival of the species.
Don't get me wrong, I think in any specific discussion about speech restrictions the bias should be huge in favor of free speech, given the obvious dangers of any too broad restriction and the incentives of people in power to put in place such restrictions. But we definitely don't currently enjoy, let's say "absolute information-theoretical freedom of speech" (e.g. including things like direct actionable threats, weapon blueprints, video-recordings of certain third-party crimes, etc). We already put up with some limits without falling into a slippery slope. 'No explicit calls for genocide' might not, on its own, be the restriction that opens the floodgates to pervasive censorship.