Speaking as an outsider, it's very interesting observing all the spin here.
A 17 year old with a rifle is "protecting a business" (Who sends a 17 year old with a rifle to protect a business?) and that's presented as normal and ok because of, you know, the 2nd amendment and all, I guess. Some people bend over backward to find ways to proclaim his innocence, and that may very well turn out to be the case.
It will be interesting to find out what emerges about his background in the next while and the reactions to it. Because, in the past, when some unarmed black teenager has been shot, stories started to appear pretty quickly about the kid's troubled past, even though the relevance to the shooting in question was not often clear, to me anyway. Does it matter that he was in trouble with the cops 2 months before? But the media muddling was obvious enough, "the kid was trouble, he had it coming." Those words were never said explicitly, I don't believe, but that's what everyone understood it to mean.
Take the statement above about the video showing that the 17 year old had been shot at earlier. OK, but is THAT in context? Why did that other person shoot at the 17 year old? We don't really know that yet, do we, yet sides are being drawn based on obvious politics, as if what's important here is the political spin.
When people believe that they have a right to protect themselves by carrying weapons in an open society, stuff like this is going to happen. You can nit pick that the 17 year old had a right to carry a weapon but you may be missing the bigger problem.