I really do not understand how the airlines allow these, since they restrict the seat in front of you and have nothing to do with the seat you have paid to use during the flight. It is no wonder the guy should have been kicked off the flight if he continues to use the device. Personally if my (already very limited reclining) coach seat was hampered by the person behind me I would be complaining to the airline directly as the seat I paid for was not working correctly. If they want to compliment my flight by upgrading me then wonderful. All I know is I would NOT be the one being removed from the flight as a result of someone else's ignorance!
Knee Defender passenger thrown off flight: I'm ashamed