Well I don't know the regs for police, but in a situation like that, where it would be difficult to determine if the threat was neutralized, it would seem logical to me to shoot until you knew for sure.
Also, it looks like possibly the guy stuck the gun out, and the officer pushed it to one side, took a step back, then ducked out of the way while the drunk re-aimed and fired. Maybe he didn't even try to shoot at first. Either way, the officer is justified using his weapon when the guy has opportunity, capability, and intent to cause deadly harm.
If you choose not to decide, you still have made a choice.
Lassev: I guess there was something captivating in savagery, because I liked it.