I really don't see the harm in this movie. Did Hogan's Heros insult the memory of World War 2 just because it made light of the Nazis? There is a lot to make fun of about the jihadists.
I would be surprised if this film actually had a lefty, anti-American viewpoint. As others have noted, these South Park guys tend to be libertarian conservative types. Many SP episodes have skewered the left something awful.
Plus this film has been endorsed by radio personality Phil Hendrie, a Democrat who is 1000% behind the war on terror, and the war in Iraq. Phil is also the biggest basher of Michael Moore you will ever want to hear. He would have done better grilling Moore than Bill O'Reilly did.
Bugs Bunny made fun of the enemy during WWII, as did a lot of other cartoons.
http://www.authentichistory.com/images/ww2/toons/ww2toons01.html
Trivia - The actor who played Lebeau/Lebeaux was a concentration camp survivor. The three main German characters were played by Jewish actors.
Back to the thread, there is a lot about the jihadists to make fun of. The PC crowd will be all over this movie.