But taken to extremes...
IMHO, you're confusing decent behavior and manners in public with speech restriction. You cannot have anything like PC floating around and preached without it eventually getting to the point where political speech rather than slanders become the focus. Years ago you never heard people using racial slurs in polite company even though they might use them at work or when talking with a friend. In fact, one of the things that used to make a couple of my friends more ticked off than anything else was how friggin polite everyone could be while making sure you knew where the appropriate restroom and water fountain were.
Every so often the Southern Baptist Churches used to all preach a sermon against using hateful names for others not like you or less fortunate than you. Everyone understood that the Pastor was referring to the use of the nword and things like, "lint head", and redneck. Sure, some people did anyway, but then they found themselves less and less welcome in polite company. IOW, society policed itself.
Among black folks, for example, there were terms (not just the nword, either) black folks now commonly apply to one another that if you used them would absolutely mark you as someone "nice folks" didn't want in their home, around their kids, or in their employ. You friends would let you know about those things, too, because they didn't want to be embarrassed around their parents by some white kid their parents were bound to be suspicious of anyway. All you have to do is study history and to realize very quickly that restraint of speech only restrains speech that those in power want restricted and has very little if anything to do with making society less threatening, more friendly, more accepting, or anything else. Societies where the members want to have a civil society do quite nicely without the government dictating anything to do with speech, thank you. In addition, in every case where government intervenes in something so basic as speech, taking that inch just convinces government it's the ruler.
JMHO