I think you misunderstand, people should be free to be racist as they like. But by saying that so and so people are subhuman scum, it's only fair to allow other people to call you subhuman scum and knock your teeth out.
since i defended you before i am duty-bound to inform you that i think this is really, really dumb. i don't think anyone has any obligation to stand there and withstand verbal abuse of any kind, unless stipulated by legitimate consensual contract (lmao). i think that Tyler the Creator might have had some really good advice for this- something about walking away from the screen
really, there are very few folk running around being overtly racist IRL. of course anonymity and power-distance of internet allows people to
a) express racialist views that are not socially acceptable where they are
b) troll motherfuckers that they would not troll IRL
but someone doing this on public property would almost certainly be removed or arrested by the authorities; someone doing this on private property should be subject to the property owner's wishes or else leave.
further, "racism" needs to be operationally defined. in your examples, you use a hypothetical individual that believes and loudly professes that all races aside from his or her own are subhuman; not really people. that's a pretty fucking extreme case, don'tcha reckon? even seasoned e-racists don't generally take that stance.
does someone that prefers the company of certain race(s), yet keeps it to themselves deserve to be pummeled? what about someone that openly prefers certain race(s)? is it the preference that earns a deserved beating, or is it the profession of preference? is it the use of a slur? is it how angry the subject in question gets?