So the liberal speaker has 1st Amendment rights, but not the offended audience? And if you think "despicable" speech that divides our nation in a time of war deserves sitting on one hands followed by polite applause, well, YOU are the one with a problem.
Say W or Rummy gave a commencement speech and was drowned out, you know you would be cursing the audience.
farting in his general direction would be good, but that's easier for oldsters than youngsters to do.