Maybe in case he screws up something? Although you really should just use a NAND backup for that.You can use any CIA installer: FBI, BBM, DevMenu, SOON, NASA...
You can't autoboot to a CIA installer in a9lh but you could using menuhax (could rename FBI.3dsx to boot.3dsx). Why would you want to though? Surely you want to spend more time playing games than installing them.
How would it help? If he screws something up with his NAND he probably wouldn't be able to boot into the CIA installer anywayMaybe in case he screws up something? Although you really should just use a NAND backup for that.