Dao was non-violent so in theory there was no need for him to be harmed. Who did Dao harm? If he harmed no one, then the airport security escalated force.
Let’s see how that works if you come home and find a stranger in your living room who promptly sits down in the middle of the floor and refuses to cooperate when the police arrive.
We dont know exactly how he got harmed, was it because of the difficulty in removing a passenger who might have been physically resisting at the time? Was it because it was difficult to pull him over the seats? I dont know that he was purposely "beat up". He asked for this, and he got it. He is also going to get a nice payout regardless of whats "right" or "wrong". Basically, that doesn't matter, its public perception, in the end. But for me, I like to remain as objective as possible. I leave my outrage and emotionality to my younger, liberal days.