Further, Olberman is a perfect example of George Orwell's "minute of hate." Go get a copy of 1984, highlight the passages on the state sponsored mass hate of the enemy of the day. Lay it open where your dad will see it. Other than that, I share your pain -- I have family who won't speak to me because I'm so "hateful", I haven't gone to Thanksgiving for the last several years, and one uncle threatened to kick me off his land because I had a bumper sticker supporting a republican congressman.
C.S. Lewis, in one of his science fiction Christian allegories, makes the great point that God gave us hate so that we could have the proper attitude toward sin. We turned it around as a weapon against our fellow human beings.
It’s sad when politics can cause that kind of divide within a family but it doesn’t sound like you’ve lost too much with that uncle. Last Fall we had any number of people in our extended family not speaking to each other, but by Christmas some semblance of peace was restored.