I think you're missing the point: his daughter knows those characters through pop culture. She wants to read those comics. But the art for those comics is clearly telling her: you are not our audience. And this is most of the store.
The male characters are male power fantasies, and appeal to his son. But the female characters are not female power fantasies, meant to appeal to women. They are male idealized-woman fantasies, and do not appeal to his daughter. That is what he realized.
The male characters are male power fantasies, and appeal to his son. But the female characters are not female power fantasies, meant to appeal to women. They are male idealized-woman fantasies, and do not appeal to his daughter. That is what he realized.