Speaking of reality, this flight was not overbooked. It was full, but the airline sold only as many seats on the flight as were available.
Everything else in this article that flows from the premise that this flight was overbooked is pure bloviation.
The problem is that United pulled paying customers off the flight due to a crew scheduling problem.
That's why they've changed crew scheduling so that a dead-heading crew needs to be at the gate at least 60 minutes prior to the departure time so that they can bump paying passengers before they're seated on the airplane.
Dao violated no part of United's Contract of Carriage. United violated their own Contract of Carriage by physically removing Dao from his seat and because of this they will pay through the nose.
As well they should.
UAL is going to argue that they were required by law to move that flight crew. And thus they were required to take people off the plane. United will say they had nothing to do with the security guards who showed up, and no choice.
You are correct. Shame I had to wade through six replies before hitting the truth.
Meanwhile, United continues to get bad publicity, and fun with words by the public like the following:
New United Airlines ad campaign slogans:
1. “Drag and Drop”
2. “We put the ‘hospital’ in hospitality”
3. “Board as a doctor, leave as a patient”
4. “Our prices can’t be beaten, but our passengers can”
5. “We have First Class, Business Class and No Class”
6. “Not enough seating, prepare for a beating”
7. “We treat you like we treat your luggage”
8. “We beat the customer - Not the competition”
9. “And you thought leg room was an issue”
10. “Where voluntary is mandatory”
11. “Fight or flight. We decide”
12. “Now offering one free carry-off”
13. “Beating random customers since 2017”
14. “If our staff needs a seat, we’ll drag you out by your feet”
15. “A bloody good airline”