Meh, opinions are opinions, personally I really just don't care what they say. Michael Moore doesn't know about the roles of snipers, so why would anyone bother to pay attention to his thoughts anyway? Seth Rogen just said it reminded him of the scene in Inglourious Basterds with the Nazi soldier picking off a bunch of people from a tower. He wasn't saying that it was Nazi propaganda, he just said it reminded him of that scene, but he liked the movie. I don't really see what's wrong with that statement, and while I haven't seen American Sniper, and honestly don't plan on it, from what I understand there are parts in the film that the scene comparison (meaning target rich environment) would be understandable. That's people taking a non-story and trying to make it one.
Again though, Michael Moore is just "that guy" anyway, frankly if he thinks I'm a coward for being a sniper, I figure I'm probably doing something right. I don't really want him to like me.