Sure, they weren't the ones who employed the officers who removed the passenger from the plane but things didn't have to work out that way if United had considered that the passenger did nothing wrong to expect to be bumped from a flight. In fact, United had many options at it's disposable that didn't need to involve forceful removal of passengers such as:

1) Upping the compensation considerably beyond $800. To be honest, that's just not enough considering that people routinely get $400+ for moving to a flight 2 hours later and this was moving to 3PM the following day.

2) Not accommodating United employees who they wanted to get on board this flight. That should be only when you have EXCESS seats, not so you can bump off paid passengers. Here's an idea, book them on another airline's flight. If that was not possible, then that's poor planning on your part, find a way to deal with it that doesn't involve bumping passengers involuntarily.

Overbooking flights is going to be norm, a small price we pay to get lower fares. The response when it happens is the problem that is completely in the control of the airlines.