14 years is middle school. You don't need a cell phone in Middle School. If you're hanging out with your friends, do you need your cell phone to communicate? You could just "talk" to them, unless that has gone out of style. Furthermore there's almost a 100% chance he didn't pay for it and doesn't pay for the plan, further delegitimizing his complaints. Anyways, you're right- I shouldn't simply pass judgement.
In regard to the actual problem: I have a very hard time imagining "cracks on the backing." The back of the unit is made of anodized aluminum, isn't it? Or is it black plastic now? Aluminum doesn't crack, and plastic only cracks under direct force suggesting user damage i.e. not covered under AppleCare (which the OP doesn't have, apparently). The edges might be a different story, but over flat surfaces random cracks due to material defects are extremely rare. The phone still functions, so what is there to complain about other than aesthetics? If it's in a case you won't see the scratches in the first place.
Several times I've taken my macs into Apple Stores to see Geniuses- I've always found them to be helpful and courteous. Of course maybe the X factor is that I'm in my late 20s... and I had actual problems I couldn't solve myself or simply ignore due to triviality.
In eighth grade you turn 14 and in ninth grade you turn 15.
It's plastic, the housing cracked under no pressure, I'm assuming since I think I've previously seen him mention this the cracks have been there for awhile so he may have just got the chance to go into the Apple Store.