You're confusing lazy cynicism with realism. Patrick Bateman is a fictional character. The vast, vast majority of people, including even most soldiers, and definitely pretty much all businesspeople, no matter how unscrupulous, do not have the capacity to violently murder a person they know and harbor no ill will towards with their own hands on short notice.
The whole damn point behind the idea is to achieve the exact opposite. Make it someone, through whatever criteria, whom the president will have a problem killing, so he'll only do it under the most extreme circumstances.
