Airlines must learn lessons from safety and commercial problems in their own and other airlines.
In this case clearly the problem of the airline. At the point of forced offloading that the airline allowed to become
violent, there was either a policy that allowed such serious actions, there was insufficient policy or none. Hard to
visualise a fault other than the airline.
The solutions include
Immediately compensate pax and not proceed with criminal prosecution
Publish overbooking and full offloading procedure including D/H crew
Of course all safety and commercial policies need review.