Neutralisation of a threat isn't given by a specific number of shots. It depends by the gun, the way the target is hit, the target itself. Sorry mate but that doesn't sound right.
Neutralisation is given when the target doesn't pose a threat anymore, AKA when you have the upper hand and you have him wounded, unable to move a d held at gunpoint.
Which is how these two found themselves when he shot them again.
By doing that, he shot at a target that, BY LAW AND NOT BY ANYONE'S JUDGEMENT, wasn't posing a direct and immediate threat to him, so unjustifiable use of deadly force.