the knights code thing was a really elegant solution, though it only worked because the boy had the grit to stay up all night studying.
She might be a little mean about it, but overall, her actions are doing more good for the boy than his father ever did for him. Not only is she kind enough to let him stay so he doesn't get beaten by his father, she's also making sure he studies. Probably if he stays with her for long enough he'll become a decent enough person to at least not immediately ruin himself once he enters a social situation on the future.