I agree that United should have handled this differently (say, by making one of their employees take a later flight after two rounds of negative response) ... but screaming? a violent confrontation in an enclosed airplane? ... com’on, man! Way overblown and not very well handled by the “professional” as well (who now still must take a later flight despite their misdemeanor.)
Oh, I’m pretty sure employees can’t ride if the flight is overbooked and they have to get a paying customer on. That wouldn’t make sense.