I'm pretty sure that's not how he wants things to go hahaha.
Its not even a win for me either he gets my games and I get to have to share my account... as a famous line once said "Joey doesn't share food", neither do I share my steam account >:(
You can stop him from doing that by simply doing a steam share :v that's a win win for you both. He'll have access to your games and you can keep your steam account x'D and if he misbehaves you can threaten him to end the steam share haha. Pretty good idea, no?