I don't know what I would have done in that situation. My biggest pet peeve is ignorant authority and I've been a fighter my whole life. I just don't take crap from anybody. I would hope eventually to mellow out but at 57, perhaps not. :-)
I've run through in my head what I might have done in that situation and all scenarios turn out ugly. I guess it depends: would I ever want to fly again?
I'm betting that in discovery, it'll be found out that United Airlines in Chicago is instructed to use Chicago Airport Police to do their dirty work for this because the Chicago Police would tell them 'this is a civil dispute over an airplane seat, you work this out.'