Because there is no moral equivalence between the despotisms of the middle east and the elected government of a secular democratic republic. Overturning tyrany is good. Attempting to overturn democracies in favor of mob rule is bad.
You get someone elected, someone who is far from perfect but he's the only likely candidate to win, so what can you do. And then that person has 4 years to screw you over. That's not just.
I think people tend to conflate liberalism (in the classical sense), and democracy. You can have undemocratic liberal states (the Austro-Hungarian empire was a good example).