Someone on a different message board put this situation very well: By the letter of the law, United was correct - morally, they were not. Their 'contract of carriage' allows them to IDB (Involuntary Deny Boarding) to passengers due to overselling, and bump people off at-will. Depending on how delayed the passenger would be to their final destination, they would owe compensation (up to a max of $1350) for the trouble.
Unfortunately, the way this played out was pretty terrible. My hope would be that events like this could move United (and other airlines) to having more transparent overbooking policies and compensating people fairly, but that's not likely.
Unfortunately, the way this played out was pretty terrible. My hope would be that events like this could move United (and other airlines) to having more transparent overbooking policies and compensating people fairly, but that's not likely.