I don't think it's going to be that easy. The problem is that the law Kyle was charged with was contradicted by another law that described the type of weapons minors were allowed to have. You can't very well have a law that says "Minors can't own guns" and then another section that describes the type of guns that minors are allowed to own without leading to confusion.
But there's no law contradicting "Minors aren't allowed to purchase guns", nor is there a law contradicting "You are not allowed to give a gun to a minor."
Now a lawyer may argue that having a law saying minors are allowed to have a certain type of gun, but they can't purchase or be given said gun, is nonsense, but that would just be the the way it is -- minors could posses a type of weapon that they have no way of legally acquiring. And that seems to be the case.
But I'm not a lawyer, so who knows. Regardless, the feds have him dead to rights on the straw purchase if they ever want to charge that, and it's certainly not any moral absolution that Dominick and Kyle both thought that what they were doing was illegal and they did it anyway. Hopefully Kyle is a good bro and lets some of his Tucker Carlson money trickle down to his dumbass friend.