It's all very sketchy. If he truly almost said "army of one," which would have fit with his previous sentences, then it sounds like he was aware of the plan before it went into action.
If he did stop mid sentence on army of one, it could also be out of sympathy for the situation and victims. The guy might have realized that he was saying something that would be seen as highly offensive seeing that the guy just unleashed hellfire on a group of people with many dead. He could have realized how inappropriate that would have sounded.
Exactly.