Again, the Citizen even being armed is drilled into the mind of the police officer as being a threat.
The police are not very well trained in deescalation,* rather they are increasingly trained to project force and certain LEO hiring practices indicate a bias towards those who are essentially bullies.
This whole thing could have been avoided with application of Proverbs 25:15 and Proverbs 15:1; respectively:
Honestly, this mentality of "he has a weapon so he's automatically an enemy threat" would never fly even in a literal warzone, because you'd end up friendly firing on your own guys and/or allies.
Indeed, considering all this, I wonder if some police are being trained to assert their authority in such confrontational and abrasive manner to cause escalations and therefore more police shootings, and therefore make police officer work less safe statistically which the government can use as another push for gun-control: It's for our brave, hardworking officers who ought to be able to go home to their families safely!
(Yes, I distrust our government that much; after seeing the recommendation against indictment of Hillary after essentially proving her guilty, I wonder who doesn't.)
Drilled? Its simply common sense. The officer freaked out. He saw a thug looking, urban type black guy, reaching back for something. He knows the guy has a gun. And he freaked out. You can paint this however you want, but I dont need to make that reach. Not needed in this case. Cop freaks out when armed black man reaches back to grab something. Simple as that.