Like fear, he did away with useless emotions such as shame, guilt, and regret long ago. He does precisely what is necessary, regardless of the consequences or conventional morality.
So it is with Evey. Most would consider his actions immoral--she certainly will--but in his mind, it would be far worse to allow her to remain forever shackled by fear.
He goes about his task diligently, fervently, striving for the utmost realism.
And all the while, a small, terrible voice whispers in his ear, "You are enjoying this, aren't you?"
And there lies the true ignominy of the situation.
He is.