They finally outlawed that silly knee-defender device.  Here's the latest info from Onboard Updates:

United Airlines has decided to prohibit the use of devices that prevent customers from reclining their aircraft seats.

One such device, the “Knee Defender,” is currently available for sale via the Internet. United’s Engineering department conducted extensive testing on the device. Results indicate that it can hinder exit from a seat in an emergency. Also, in an unstable environment, where clear air turbulence can occur, the device can break the tray table.

It also has the potential to provoke disputes among passengers, which may lead to an increase in disruptive behavior in flight.

Therefore, effective immediately, United will not allow the use of the device on board any of its aircraft, including Ted and United Express.

United Airlines' seat pitch in Economy Plus® (UE) is 35 inches and 31 inches in regular UE seats. These dimensions provide a comfortable ride for any traveler.

If you find the device being used, ask the customer to remove it and report the incident to Onboard management.