So you're saying a member of the executive branch does have a prerogative to refuse to enforce laws he finds immoral?
Sure he does. Just like you or I do. But just like you or I, he must stand in judgement for his actions. The public may totally agree and if there's no public pressure to "take corrective action" there's likely to be none. On the other hand if the howl goes up, he may find himself in deep crap. Just as an easy example, you may find a kill a serial child rapist while not in the act. You may be charged with murder or you may slide because of the previous horrendous and prevention of future ones with the public's approval.