In my own opinion: he acted on an impulse, regardless of the consequences of his actions and the right/wrong factors involved, and will get the results thereof. He made a choice, just like the woman chose not to A) quiet her child B) move away from him, maybe even get an attendant or security C) simply leave. He could have just left, too. It was definitely an unnecessary and unlikely event that could have been avoided, but it happened. Now, everyone is dealing with the aftermath.

Action > Reaction.