It's weird to me that the offended party thought the joke was trying to "own the libs." It seems to be an example of the common genre of jokes that liberals make about how hard it is to have holidays with extended family. The joke is told from the perspective of a liberal who is on his/her best behavior at the beginning of the meal and grows more frank as he/she drinks.
Anyway, my Fox News loving father-in-law is no longer with us, but when I used to head up to see my wife's family for the Holidays, I'd amuse myself by coming up with one kind of unhinged liberal position just to get him worked up a bit (to be clear, he was a great guy who just had some standard old guy Fox News opinions). My favorite was the time I told him I opposed circus animals.
