Plus the fact that the "A man, nothing more." Line could be referecne to what Kreia stated once: "He can not be called a man any longer."
And Visas says he is. So we got a lying Kreia, and a Nihilus that seems to be a man. I'd say it could be the face of the exact opposite of the Exile what's beneath the mask: A man, purley darksided.
And Visas confirms that.