Oh, you never know if outright telling them to kill each other and subjugate them is enough to stamp out any altruistic feelings they may have! I have known a few particularly heroic people who wouldn't have been deterred by that.

[She married one, some time before she became the Other. Oh the times before continental domination scheming]

It'd go poorly, there's no doubt. I believe Iago is more useful alive than dead, so let's avoid putting him in fatal danger ourselves.

[If someone kills him then alright, that's fine, but she'd like to avoid any situation that'd lead to she or Rembrandt causing his death, yup]