It was a clever movie. It illustrated time and again that liberals were smarter than po-dunk conservatives (by their standards), until they ran up against an intellectual conservative. At that point even they had to admit that they were wrong, but they still wanted to kill the Rush-type character because they disagreed with his ideology and had become completed corrupted by their own successes.
That the liberals were tricked into drinking their own poison was the ideal way to end the movie (and carried the hidden message that liberals can be poisoned by their own views).
Also, the Rush-guy's answer to the "would you kill Hitler before he assumed power" question was brilliant. The Conservative said no, first I'd challenge his ideas and try to get him to see the better way (and he continued to do that with all of his liberal hosts) because my arguments would trounce his on a level playing field.
Hey, Hollywood also produced Red Dawn. Conservative movies do get made in that town (e.g. Firefox, The Green Berets, The Outlaw Josey Wales).