As I have mentioned before, I'm 6-foot-2 and all leg, so I'm very sympathetic to folks who complain about legroom. However, like many tall people, I also have a bad back, so I'm very sympathetic to folks who want to recline their seats.
Heck, I'm even sympathetic to the airlines that are cramming people into planes with the wild abandon of college freshmen filling their trunks for summer break.
But it's hard to sympathize with anyone in this story: United Airlines diverted a flight after a passenger used a "knee defender," apparently in violation of United's clear policy, and refused to remove it when the flight attendant told him to and the traveler who was thus prevented from reclining threw a cup of water at him.
Let's review some airline etiquette here: The airline owns the plane, not you. You are renting a seat from them. They have chosen to rent seats that recline. If you can't handle someone in front of you reclining, you have a few choices: You can politely ask them not to recline, you can purchase a more expensive seat that offers more legroom, or you can find another mode of transportation.
What you are not entitled to do is modify the seat to prevent it from reclining, no matter how unfair you feel life is to us tall folks. The person in front of you purchased that seat with the expectation that it would be able to recline. If your legs are actually preventing movement of the seat (which happened to me on one particularly tight flight), that's tough luck on them. But you should not go beyond what nature has given you in the way of reclining prevention.
Grown-ups do not throw drinks at people unless those people have made indecent advances in full hearing of your spouse or grandmother.
Neither of these offenses really merits diverting the plane and inconveniencing all the other passengers because you, the airline, made the mistake of selling adjacent seats to two overgrown toddlers with size-12 egos in size-four souls.
Megan McArdle is a Bloomberg View columnist who writes on economics, business and public policy.