Being further along the psychopathy spectrum isn't all sunshine and daisies and rationality.

Instrumental learning is also interesting. “Instrumental learning involves learning to commit specific behavioral responses in order to gain reward or avoid punishment.” [ibid, pg 51]. Psychopaths have issues with specific forms of this, particularly passive avoidance and response reversal. In passive avoidance, the subject must learn to avoid responding to thing that will give them punishments, while response reversal is when the subject must stop responding to a stimulus that was once a reward but now punishes. The impairment of the first has been repeatedly demonstrated, while Blair uses the example of a card game developed by Joe Newman to demonstrate the second. In that game, participants must decide whether to play a card or not. At first, playing is always rewarding, but as the game goes on the probability of playing being rewarding decreases, and eventually it will be primarily punishing. While most non-psychopaths do learn to stop playing once punishment becomes too likely, psychopaths do not, to the point of losing all of their points.

http://verbosestoic.wordpress.com/fearlessly-amoral-psychopaths-autistics-and-learning-with-emotion/

Basically, I fear you are committing a sort of "straw-spock argument" about rationality, where you assume in the absence of evidence that someone with more muted empathy must be pursuing their goals more rationally.