On face value, in this case if anyone had a stand your ground justification, it would be the kid who was shot (and based on the end result, rightly so). The old guy approached him in the car and started the confrontation. The were not on the shooter’s property. He went out of his way to start the confrontation. Even if the kid who was shot had a gun, he was, in essence, in his property, being in his vehicle, and was approached in a threatening manner. Not much different than if he was in his home and someone came banging on his door threatening him.
That's kind of the way I see it. The kids had the same right to self-defense that he did.
If seeing a gun in another vehicle makes you feel threatened, then seeing Dunn reach for his weapon and load it would do the same. If they had had a gun wouldn't they have the right to use it given his actions??? and yet they drove away.
If Dunn tries the self-defense defense it will be a mockery of those who do use their weapons for self defense.
Too many folks imagine stand your ground applies only to someone who is armed. In a few minutes we can expect to find some of them on this thread arguing that if the man thought he saw a gun, it was a good kill ~ even though there was no gun.
At least one of them will tell us "it could have been a gun".