There are two issues. The night that it happened. And in the future. The solution going forward is bump people earlier and if delays happen, they happen.
Okay, fine, let's pretend there are two issues.
#1. "The night that it happened." Did United Airlines have
any other choice than to eject that passenger? Any answer other than "yes," with any other stipulations or right-wing baggage is too much. Just write "yes."
#2. "And in the future." Regardless of your plans, suppose in the future someone is seated on the plane and airline industry corporation wants to get their ticket for an employee. Seated passenger doesn't want to leave their seat. There are other passengers some of whom may want to leave for more money. Does United Airlines have
any other choice than to eject that passenger?