I love the Mossbergs. There are a lot of folks who dont like the rattles of the older ones. Never bothered me, I dont run with my guns. I shoot one in a 12, my son has a 20 and my daughter a 410. All three have killed deer.
I looked up the Superbantam, never seen one in person. Looks like a nice setup. My only fear would be the weight or lack of in the stock. If he is a big boy probably wont matter.
I say go for it. Let us know when he brings that deer home. Love it when they get it to hunting. Have taken many first timers(neighbor kids) out for the first time. Good luck, thanks for bringing another child to the hunting world.
Lonny