I don't see a problem, in theory, with teaching a kid a lesson for being a little asshole. My friends and I did this sort of thing in a similar middle-class neighborhood growing up, and now I see it as idiotic and annoying. BUT, shooting a kid with a freaking shotgun? The crime better be a little more severe to warrant something like that. This is an absurd overreaction to something very petty, and he deserves to do hard time for it.
It doesn't help that he hid in the bushes and ambushed the kids, either. Christ, a paintball gun would have been OK, but this is just sadistic.