Beyond that at least in the US the Constitution only restricts the government (and the states by virtue of the 14th amendment) from restricting our rights to free speech. Private citizens on their own property/workplace/areas they control can restrict you however they want. If you don't like it you don't have to go on their property.
That said the way I handle this on my forum is having a separate debate hall and arena where the gloves are off and anything goes. The rest of the forum you have to play nice.