Then there's walking into an active lecture an hour into it. It's just plain rude and there's no way to avoid distracting people unless it's a very large lecture hall.

yes, it sucks that to make deadlines he can't visit each class on separate days...but that does not make his actions any less rude or distracting. Furthermore, e-mailing the professor about how HURT you are that they called you out on your rudeness is just stupid. Particularly since the student was obviously just trying to bite at the professor.