Well... I wasn't there. But it sounds like the cops happened to come up on the guy just at that moment. Cops have a tough job. I find it difficult to second guess them a lot of the time.
I mean, black white or indifferent, if a cop tell you to put down your weapon, you better do two things real fast:
1. FREEZE. Don't move a muscle.
2. Say "yes sir, I'm putting it down", as loud as you can.
And then, while the rest of you is still frozen, gingerly take the weapon with two fingers and lay it down, and make sure the cops can see the rest of your body while you're doing it.
If you get very VERY lucky, and the cops can hear you and they haven't had "too" long or stressful of a day yet, you stand a snowball's chance of exiting without a new bullet hole. Or twenty or fifty