You know, I came here to make the same argument the rest of you are making, but I was struck by a realization.
Speech codes like this are a necessary result of outlawing other forms of punishment. If you value free speech, you ought to legalize and value even physical reprisals to offensive speech.
People don't care for grave dancing. Nor many other offensive things that are "merely words." In the founder's time, such boorishness would get you beaten and tossed out of town (possibly even tarred and feathered with the implicatation that you are not welcome to return without abject apologies) or challenged to a duel.
This is a part of the idea that "An armed society is a polite society" because you may have to back up your impolite words in a test of arms. Thus, people tended to be more polite as impoliteness could lead to your death.
When we decided that boorish louts were not allowed to be dealt with physically, it inevitably lead to speech codes like this because people don't like boorish louts and desire an enforcement mechanism to deal with them.
Now, don't get me wrong, I am VERY much opposed to speech codes and am well aware that many of my beliefs would get me in trouble in the politically correct speech codes of Great Britain and Canada. I am simply saying that I can understand reasons that likely have led to their existence.