If it were posted by a confirmed Leftist, you'd have had no trouble calling it anti-American hate.
It could have come directly off an Al-Qaeda website. Just because the poster is presumably on the Right in NO WAY dilutes the absolute wrongness and bile he professed.
Well unfortunately not everyone is as patriotic as you are. Also, remember there are people who are 'one issue' types and they don't necessarily have an opinion on other issues. Some religious people believe we are in the mess we are in because of things like abortion. I don't agree though.