You have to be a fucked up human being to even have it occur to you that other human beings think that way. Normal people , if they even imagined this plot would think "nah that's absurd, no one thinks like that. The audience won't find it convincing".
But this matsumoto freak thought "ah yeah what about a father who wants his daughter to get raped by a man with a big dick so that she doesn't fall in love with a man who has phimosis like him and then the daughter tells him about his wife. Yes this works"