The joke was only botched because the audience that would find it funny is not "the public" but a limited group of arrogant, classist, elitist, lefties.
If he told that joke to that limited audience the room would be filled with har hars and yesses.
Sopt on. Liberal "humor" often has a theme of condescension attached to it. I've worked around many liberals for many years, and they are precisely what you say: arrogant, classist, elitist, lefties.