That's bizarre. Was he annoyed by their seat reclining into him? Was there some previous altercation?

This is probably a TravelBuzz thread, but I once had a woman in front of me who thought the space under her seat was for trash. She put newspapers, used food items, and then newspapers again, right on my feet, even after I handed each item back to her each time, with a polite, "excuse me, is this yours?" That was probably ignorance, though, not douchiness.