From a purely customer service conflict resolution standpoint, the fact that the guy claimed to be a doctor gave whoever was handling the situation for United a very easy out and a way to move on to the next person. I wonder why they didn't take it.
Why does it matter if the person is a doctor or a janitor? He had a valid ticket, was assigned a seat and was already on the plane. They could've simply offered more money and there would've been takers, instead of all this nastiness
If I were in a customer service position where policy dictated I kick the guy off the plane, and he did not cooperate, I'd honestly look for any way to avoid the whole police ejection bullshit. The passenger being a doctor gave those customer service people a pretty good out, in case they needed to defend their actions (to defend skipping over the guy who refused to get up and leave, specifically) to either their management or to the next person in the crowd to be picked to give up a seat. I am surprised they didn't take it.
I wasn't commenting on the wisdom of the policy.