I also went with "did not vote." I don't think of Ennis as paying much attention to politics.
If he had voted, I'm sure he'd vote Republican, because he's a conformist and most people around him would be Republicans. Also, I don't like to think about the famous deleted "hippie scene," but his behavior in that scene was pretty conservative.
Good idea for a poll, Kerry. How about a parallel one about Jack? From what I've seen, there may be more controversy regarding his political views.