Sounds like he just doesn't get the hint! Have you ever just said "shut up about politics already!!"? There is a kid in my dept that is like that. His "logic" doesn't make any sense and he refuses to listen to others' opinions on politics but talks about them constantly. I started just getting up and leaving the room. It might sound rude but some people just don't get it! I refuse to talk politics unless it is 2 people discussing differing opinions while being polite. Same with religion. I enjoy learning about others' point of views and finding new ways of looking at situations. But the second they start pushing their opinion as fact I just leave. I don't even give a warning. I do it to my bf too. If he is talking about the same thing (complaining usually) day after day, hour after hour...I just whip out the ol' trusty iPhone and stop paying attention. And I make it painfully obvious that I'm not paying attention. That's all they want. And you getting upset is still attention. Flat out ignoring them will get through faster than logic.