As you maybe know, iTunes is a user-friendly database : you feed it with all your music and it organize and manage it for you. It's very efficient but many people doesn't like a software that manages their files in its own way ...

If this kid is used to iTunes, he will loose a lot of user friendlyness ... The good new is that he can probably just take the album folders in iTunes music folders on his PC and copy it to the media player. If this player is AAC compatible, it should play the music without any problem. But it will probably not show the cover or the lyrics, and maybe it will not organize the tracks properly ...

Maybe you should search internet for real life tests of people who used a player with iTunes.

forgive me for a more personnal statement, but if he was stolen twice his player, I believe there is a lot more important problem to solve than the device replacement ...