kcdist raises excellent points.  Naughty Dr Dao had a record for diddling his patients, which, in the medical profession, is considered lower than a snake's belly.  He seems to think the rules don't apply to him, and his behavior on this flight is just more of the same.

The truth is United *did* have the right to ask him to deplane, although we may find that distasteful.  But then, of course, they couldn't have managed the situation in a worse way.  

Dr Dao has now won the trashball lottery, and he probably collected six figures.  United could have played hardball with him, and dragged his name further through the dirt, but the negative publicity would have been appalling.  Anyway, a hundred grand or two is basically the change down their couch.

If airlines are put in a position where they can no longer overbook--  based on statistical modeling--  we're all going to pay for it with higher fares.  It may be imperceptible and only amount to a few percent, but:  there is no free lunch.