I think people who consider Freedom of Speech, the principle, to be exclusively a government thing, are stupider than people who think the right to Free Speech applies to everything. Wonder why this misaligned perspective seems so popular with pseudo-intellectuals these days.

The grandparent comment explicitly draws a distinction between the social contract and the Constitution, and explicitly points to the Constitution as the mechanism that apparently protects Nazis, specifically pointing out that they aren’t talking about the social contract.

The freedom of speech is a guarantee to the people that they may exercise free thought and expression and not be subject to the use of force or fraud against them by any party, whether a state or private actor. The use of force or fraud against someone for speech you dislike does not magically cease to be a civil rights violation by virtue of being applied to someone you personally dislike. Anyone with even a cursory knowledge of history is well aware of intrusions by actors public and private to suppress speech that threatened their interests.

Put another way: All men have a natural right to the freedom of thought and expression, and no one cares what dead old men thought when they drafted their particular laws. This is about what matters to us here and now. The proletariat has a need for public debate free of interference from the bourgeoisie and bourgeoisie-adjacent. Period. Full stop.