I'm not sure it's right to say that psychopaths are without emotion. I'd call self-interest and self-preservation emotional impulses. People naturally assume that AIs will exhibit those, but that assumption is driven by our experience with existing intelligences, which have all been shaped by natural selection.
With respect to an emotionless AI, the term "psychopath" is out of left field. The term "psychopath" is associated with danger because of certain dangerous human psychopaths. And those people had a whole set of motivations and impulses that wouldn't exist in an emotionless AI.
If you want to argue that an emotionless AI would be dangerous, go ahead, but the term "psychopath" is a poor fit to that case. It brings in too much extra baggage.
And I'm not sure if self-interest and more importantly self-preservation can be seen as emotions. These two are baked in into every live organism even the most primitive ones. And it would be difficult to state that these organisms have emotions. Then again depends on how you define what emotion is.
