16 year old with broken back tasered by cops

I do wonder how the cops can say with a straight face that they needed to do this. We give cops a very big benefit of the doubt, but where do we draw the line? [Link]

“He refused to comply with the officers and so the officers had to deploy their Tasers in order to subdue him. He is making incoherent statements; he's also making statements such as, ‘Shoot cops, kill cops,’ things like that. So there was cause for concern to the officers,” said Ozark Police Capt. Thomas Rousset.

Police say although there are several unanswered questions; the reason for the use of a stun gun is not one of them.

“It's a big concern for the officers to keep this guy out of traffic, to keep him from getting hurt,” said Rousset.

He just fell 30 feet and broke his back. He was no threat.

At least they didn't shoot him.