Floating shelves are fine. We have friends who've done that. You can find some that are grooved if he's really worried. The ones from Pottery Barn are really sturdy.
Since they're already in hardcase, I really don't think you need to frame them. Ditto zizibet, just use a floating shelf with an edge like these to prevent accidental "slippage". www.potterybarn.com/products/holman-picture-ledge