This is best explained in terms of Haidt's social intuitionist theory.
Explanation:
Haidt's social intuition theory suggest that the moral codes set by a human are influenced by the social factors. He describes that the intuitions are fast paced and automated process that happens within the individual and it differs from applying rationale while responding to a situation.
Hence ones' intuition and repulsive ability takes priority especially during anxiety and annoyance. Here moral reasoning does not come into play and that is the reason why people feel morally repulsive by killing someone by thrusting a knife than simply by a gun shot.
