Agree with this. Its weird this attitude on gaf that if someone has any flaws (big flaws, granted) that the best thing is to cut them off.
Sometimes thats true, sure.
I don't think having relatives who are racist, sexist, etc is that big a deal. I know thats a crazy attitude on GAF but how they think and act don't really impact me. My wife is asian (and therefore my kids are too) and I've had an aunt or two who were pretty racist to her. I told them that if they keep talking like that we won't come around to see them and they aren't welcome to visit, but otherwise I don't care what they think or do. Over time they have all changed their minds. Or just don't talk to me about it anymore, either way that works.
Your call, but maybe learning to deal with people in something other than absolutes is a valuable life skill. Just let him know you disagree with him politically and you don't ever want to talk politics with him. There are a million other things to talk about in life, and as long as he doesn't hurt you or your loved ones then who are you to dictate his beliefs and philosophies.