The police officer already had his gun drawn in a situation that did not warrant deadly force. There's your premeditation right there. Before the police officer fired the shot he drew his weapon and by unholstering his weapon he made a statement of an intent to use deadly force.
The teacher I had for my CCW class comes back to me: "Don't draw your weapon unless you plan on using it and don't fire your weapon unless you plan on killing someone."
The same rules apply to cops.
That's not enough or even the right kind of premeditation, especially not for a police officer who may routinely draw as a matter of precaution.
We civilians are in pretty much the spot your CCW instructor said. Brandishing is (usually) asking for trouble.
-- The same rules apply to cops. --
No, not quite, not when it comes to brandishing, and not even when it comes to using deadly force.
See cop who drew leather in the pool party incident. Caught a bunch of crap for it, but no brandishing charge. If you did that, you'd be hit with a brandishing charge.