Richard. We're in the same business - I've followed your posts for years. Unfortunately, I think you are wrong in this instance. Yes, aircrew and station agents can have a seated passenger removed - for a very good reason i.e the person(s) poses a danger/hazard to the flight (drunk, disorderly, incapacitated, threatening as prime examples). But not for corporate purposes. Add the use of overwhelming force (3 large male rent-a-cops?) and you have prima facie assault.

United was totally, categorically and criminally wrong with their actions. I'm pretty certain the airline will pay dearly for their mistake.

Best regards.