> In dividing official from unofficial conduct, courts may not inquire into the President’s motives.
So the hypo cannot be trivially resolved by treating the kill order as an unofficial act. Instead, for the president to be _criminally_ liable, I think (as not-a-lawyer) it has to be resolved by piercing 'presumptive immunity' for actions beyond the core powers. While there's a needle to thread, it feels disturbingly narrow.