I'm pretty sure he was also insisting on not hiring help and using him instead, even in this chapter mom says he doesn't like help and he has to be practically forced into being taken care of, though she probably should get concerned with his tendency to overwork himself, and it seems like author's way to not paint mom as bad parent while still letting him overwork himself.
Reality has nothing to do with it, to quota Serina "Nyaa" from "Dangers in My Heart": "is this some incel fantasy?" Real life stepsiblings also don't all fuck each other all of the time, not do stepsisters keep getting stuck everywhere. And just because you can't see someone's eyes , it doesn't make him rapist.