In the context, he was saying “unspeakable evil”, so using ‘bad evil’ instead wouldn’t be as good as just using ‘evil’ by itself as a noun.

I get what you’re saying in general, and I’m not such a stickler that I don’t see the value in spicing words up sometimes. I don’t like when it’s done insincerely, such as a form of gang code. Like that essay the other day about tumblr, how the girls there won’t even get their argument heard if they don’t first satisfactorily convince of their empathetic bona fides.