I'm no lawyer, but I am in aviation claims, and this will be a major claim since UA's insurance company will pay for their defense (aka hire the attorneys) and settlement. It doesn't really matter what the background of this guy is. What matters is what happened in that incident, and what was broadcasted to the world to see. This doctor(however crooked he may be) already has a lawyer who is writing up the complaint against UA stuffed full of everything he/she can think of. Bodily injury, mental anguish, pain and suffering, you name it. The suit will be for multiple millions of dollars, and yes there will be plenty of fluff in there. But UA will not want to try this case. They will settle out of court.
Imagine the defense attorney in front of the jury, explaining why UA was within their rights to treat this guy like a sack of
, pulling out rules and fine print. Then trying to assassinate the plaintiff's character. Any American jury would begin to quiver with rage that the big bad airline, with the arrogant CEO would even think of trying to justify the way the plaintiff was treated. All the plaintiff attorney will have to do is play the videos over and over, then say "so because UA employees needed to get somewhere, it was UA's right to give Dr. So and So a blooded face, concussion, and international humiliation??" They will award the plaintiff as much as they possibly can. I've been in the courtrooms for many smaller, yet similar cases, and the airline ALWAYS loses.
And don't forget the cop goons that did the actual dirty work. Their department will be sued as well. That's the way it works here in America, suits are filed against the airlines every day, but this one has major legs. UA really cocked this one all up.