Airplane Flights and Fights

Two interesting airplane externality incidents occurred this week. The director Kevin Smith was escorted off a plane-he couldn’t lower the arm rest on his seat because he was too fat. Mitt Romney asked the passenger in front of him to raise his seatback during takeoff, and the passenger tried to slug him.
I love Silent Bob in the movies, but Kevin Smith was wrong: Why should he be allowed to impose negative externalities, literally spillovers (of his excess avoirdupois), on the passengers adjacent to him? I have little use for Mitt Romney’s politics, but he was right: Why should his safety in the event of an emergency on takeoff be endangered because the person in front of him wishes to continue enjoying a reclining position?