nonononnoonon!!! because he's so little, u NEED to get him to dump his nand! Besides, using bootmii is very easy, all u tell him is hit reset X times, Power Y times, wait for a little bit... etc.... not to mention that there's not much u can do with bootmii to harm your console... only possible thing is running another app from it's SD card menu... but u wont have anything dangerous saved there anyways.
A nand dump is very VERY important, once u have this, u are unbrickable, even if u only have bootmii as IOS, and infectus + nand backup can save any wii (assuming no hardware failware)
anyways, I would suggest getting the full nand dump, and even having him use that, and it will already have HBC and his save files on it too