He's not that OP. And the similarities are in plain sight. You must think Kirino looks different because of her far more toxic personality, but if you focus on looks alone, minus the hair remember, it's there.
Really? She's an ice cold bitch. (Which alone is enough to justify hate.) She's a tsundere. She denies having a brother complex, but gets jelly when he's around other girls. Even sabotaging such encounters. She forces him to spend time her, then denies she actually enjoys it. She's a complete pervert. And despite all this she has the nerve to call out Kuroneko on her tastes.