To me, airline employees, security and passenger made some rash and unwise decisions. I see no broader significance beyond the parties actually involved.
United said that no policies were violated. The problem was that 4 employees needed to get to Da'ville. The solution ended up being to forcibly remove a seated passenger. Surely a better policy would have helped resolve the problem with a better solution than that. Policies are designed to help account for human failings like making rash and unwise decisions as much as possible. I'll bet United and other airlines will likely think this through and decide how these kinds of things should be handled in the future.