[Catfish]

So any self-declared private militia can grab their guns, travel to whatever they see fit and have a good time "defending" american values or what they think that is? While they just want some action, but not at home of course. What is the police and any official law enforcement for?

To do private intentional riot tourism with a loaded half-automatic gun seems like a case of intentionally looking for action and trouble.
Walking around privately pointing any gun (no one cares what this gun is or was especially, the case is not about bearing guns and which, but about killing) at people, while no one can know what this person walking around "proud, like a hero out of a western", not belonging to official police force, is doing or about to do.

What about some black 17-year-olds with guns, patrolling the streets in other cities than their own due to their right of free movement, to quench riots, how do (white) people look at that?

Pleading not guilty, not even a hint of self-doubt "I did nothing wrong, i was defending myself"?
If this "poor, harmless kid" gets out free i am sure we will hear of him again, probably after his next provocation.