sorry but you sound like a horrible brother. at least he's not playing gta on his xbox as what that would teach him would be even worse! or playing mass effect as heaven forbid he'd see alien porn!!!
he's at school and is learning a new skill. this'll hopefully get his interest in fixing and solving problems and kick start an interest in something new. how horrible are you to try and stop that because he gets around a school proxy. i'd hate to have someone like you on my family, i had to double check to make sure you said you are his brother and not his owner.