Quoting an authorities opinion on this matter is kind of oxymoronic when their opinion is that this isn't something to be dictated by authority. One wonders if it isn't slightly self-sabotaging of them to take this position.
But if it doesn’t square with the rest of the language, especially since negating it somehow still means the same thing, can we really accept it even if some grand institution like “Merriam Webster” adds it to the collection?