Kid should've pulled a Casey bird flipping move ... you know, wipe away a fake tear with your middle finger.
You're not giving this kid any credit! He's probably not as stupid as you think. I'm betting that this is another crazy looking for his 15 minutes of fame and some monetary benefits from this case. He'll be all over Inside Edition, Entertainment Tonight, etc. giving his "inside story" on why he did it, etc. and he'll be getting paid well for that, too.
ETA -- based on that video, he was totally doing it to get it on tv and not giving it to Ashton. He looks directly into the camera as he does it. Kid was well aware he was on tv and tried to pull this off. Granted, wrong thing to do, but the kid thought he could pull it off and be a "hero" to his buddies.