I've long thought of the First Amendment to be that directional, less about the speaker and more about the listener. I want to hear non-mainstream, non-approved political messages. That is the only way for me to know if there is a better way according to my principles or whether my principles need re-examining. Jeff Goldstein has yet another brilliant post on the necessity of meaning being set by the speaker of words than making the meaning contingent on the listener.
Here comes the Lone Libertarian: I have no responsibility not to speak offensively. I may speak offensively if I wish, and I would then accept that people will be offended and that they may react in accordance to the offense. So long as that reaction remains within their own power, is within the power of other individuals who hear of the incident, and does not involve the power of the state to levy punishment, then all is good. Please note the distinction: Joe Blow may take offense and act upon it by shunning, but Dean Joe Blow of Public University may not act with his power as Dean to punish the speach.
I choose not to offend, because I value the respect of those with whom I speak over whatever value may come from uttering offensive words. Hence, I seldom use profanity on this blog. Whatever virtue reflects upon me, whatever respect comes from my civil language, would be entirely nullified under a speach code. Yet another way that the current culture devalues language.
One last thing: the practice of current post-modernism places primacy in the receiver of words, thereby making the words change to the world view of the listener. By doing so, the practitioner of post-modernism consigns their pupil to an intellectual stasis. Words can have no impact if they may only go "Splat" upon a closed mind.