i think you're hung up on "minor".
17 yo, out of HS (or had met minimums), had a regular job...I don't see him maturing dramatically in the few months between the incident and his birthday.
His parents could have signed for him to join the USMC, so he's mature enough in the eyes of the law and his parents to make adult decisions. I can check the timeline, but it's in my head that the parent dropped him off unarmed, and he went to his friend's house later and retrieved the rifle...i might be wrong, it doesn't change the lack of criminality by the parent.
this isn't a 15 yo with mental health issues who's parents bought him a handgun and gave him free access...those people are being prosecuted (as they fukn should be)
and at the end of the day, he's the only one of the people involved in that altercation who acted responsibly and within the law. He didn't escalate the situation by firing his gun into the air, he didn't assault anyone with his illegally-possessed handgun, he didn't try to start fires and assault people who intervened, he didn't use his rifle as a blunt weapon and try to cave someone's head in...
the people who bear the blame in the situation are the BLM organizers who allowed "Antifa" (just anti-social idiots who wanted to start fires and break shit), and on the Kenosha PD/SO/WI State Patrol who did nothing to protect businesses from those anti-social idiots.
Power abhors a vacuum.
He circumvented regulations to obtain a firearm.
Clear demonstration of lack of respect for firearms and poor gunmanship.
My grandad would have nipped that shit in the bud right there.