"Killed hated rival" opinion bonus

I was just thinking there should be a character bonus for killing the rival of another character - it never ceases to weird me out that if I'm playing as Robb or Stannis and I manage to execute The Mountain and Cersei, The Hound and Tyrion hate me for it - sure I guess they might have wanted to do it themselves, but it seems like an oversight that there's no bonus to removing a character's hated rival lol, particularly when killing a relative brings such opinion penalties - given the "killed my lover" modifier exists a "killed my rival" version should be possible