Still.. Its basic fandom etiquette to not let idols etc that you are making fanfictions of know about your works. Artists and authors intentionally jumble up names and/or use code names when making certain kinds of fan works for this reason... He already does expect it, he is just understandably weirded out by it.
Side note if its relevant, my comment was made when only EP 1 was uploaded

Idk yall I think it's valid for someone to dislike the idea of people making fanfiction about their older brother, gay or not. Her reaction makes it seem as if him saying that would have personally hurt her when it really shouldn't be