You cannot ever know the consequences of inciting violence or a disaster, for all you know, one of the two who just left an IED at an AFB were inspired by their cries. I don't think the founders ever envisioned people being protected so they could rant and call for the destruction of the very country they were in.
If the founders intended public calls against the USA as evil to be destroyed inviting others into the cause as part of protected free speech, our Founders did indeed set a very high goalpost on which for the USA to survive.
These people were not merely protesting the war, they were calling for outright disobedience, revolt and opposition to the USA as evil itself. Gee, that is one farging generous but stupid protection. And no good can come from it--- we are literally just begging for trouble here.
At the very least, the FBI needs to watch these people very closely, and at worst, a few of them need arrested and brought in for sedition and trying to incite a revolt.
Just free speech? I don't think so--- I've had some pretty vile attitudes towards a few democrats in office or their running of the country, but I never went out to a public city market and held a rally denouncing the country as an evil force in the world to be destroyed.