For example, saying "niggers should be lynched" is undeniably immoral and terrible and wrong, and it can have awful consequences. But the statement represents an idea, probably motivated by some kind of moral or political judgment,

The problem with using lynching as an example is that in constitutional terms it's pretty much the ultimate nightmare scenario. During the peak of the lynching era in the 1890's you basically had entire communities rising up and murdering folks in some instances simply for something they said or were rumored to have said. It went on for 80 years in the south and it began almost immediately after federal troops were withdrawn at the end of Reconstruction.

Sure to some degree you can make the argument that lynching ain't what it used to be but there are challenges there in terms of overcoming the long memory of two interested parties: black Americans with direct ties to the Reconstruction era South, and the Federal Government. As a rule governments aren't too keen on the idea of armed mobs running around killing people in the streets regardless of who the victims are. It looks bad, it's bad for business, and sooner or later the situation is going to have to be dealt with before it spirals and presents a much broader, more acute threat to governmental authority generally. That last part took a while in the US because the local authorities quickly discovered that the terror aspect to lynchings was even more useful than the actual murders themselves. That terror, carefully leveraged and fully exploited, became the foundation for southern segregation.

All of that was done in the name of free speech and "free" every other thing. So although I agree with your point you've got to watch yourself when you start picking examples because there's some serious history behind a lot of this kind of stuff that cuts to the constitutional bone.