the US has a violence problem rather than simply a race problem
It has both, surely? Disproportionately this is a violence problem that is comprised of the armed wing of the government shooting people of a specific racial origin. Plus a smaller number of people from that racial group shooting back at the (overwhelmingly white) police.
I can't see how the police could expect to get away with making up something like that.
I can (not saying they did make it up, I've no idea, but I wouldn't discount the possibility so fast). The legal system is obviously hugely biased in favour of the police, and some US cops are getting away quite literally with murder. In the current climate, I have great difficulty trusting the US police on anything they don't have video evidence of, not least because on several recent cases across the states video evidence has proven them to be lying their asses off. And they're still not getting convicted when that does happen.
Whilst I clearly don't condone pointing guns at the police, we are talking about a country where the police shoot black people, many of them totally innocent, on a not irregular basis. I can absolutely see why some black people in the current climate may simply have reached a point where they regard the police as simply a body of people trying to kill them, and as such will be much more inclined to wave firearms at them on the grounds that for all they know,
the cop might shoot them anyway. Especially if they're actually involved in crime, but more broadly as well; a perception among US police that black lives are expendable does genuinely seem to exist and be worryingly strong. The police in places like St Louis are in a total legitimacy crisis in my opinion, essentially being wholly unsupported by the communities they're theoretically working in/with - and a very radical change of policy is needed to try and cut down on what may well soon become a cycle of reprisals, violence and killing.