Okay, so sometimes I'm guilty of being an armrest hog. But if I have an aisle or window seat I usually let the poor guy or gal in the center have the armrest… because that seat is always terrible.
Now, regarding what this guy did, he may have gone just a bit too far. He pushed that guys arm off in a pretty aggressive way. And that look says it all. There was a point or two there when I thought that guy was going to swing.