I don't think the OP screwed up at all. He was the only one there and called the play the best he could.
Also:
- TSA even says don't call 911. Call some random 10 digit number
- The United agent wasn't calling the cops (or perhaps they know the 10 digit phone number for mall security) and was not acting as if it was an emergency
- Not everyone likes cops, or feels safe in their presence or feel that level of escalation is the first response
- In real time people respond without clarity of thought and purpose.
- Some of the most adamant people on this thread who are security experts who work for I can't name it on FlyerTalk are giving bad advice
That being said, without any martial arts training I would have perfectly roundhouse kicked that guy in the face and detained him with my homemade restraints made out of duct tape while calling for SWAT backup with my free hand. Not one drop of my hurricane would have touched the floor. It's cool, I know what I'm doing. I'm an Eagle Scout.