It’s a mocking corruption of his name, Ms. Ambrye. “Nauplius” becomes “Naups” becomes “Napkins.”
I think it’s mostly one of Miz’s usual diminutions and trivializations of people she doesn’t like (which actually I don’t think helps her cause, since she tends to apply it even to people she’d presumably like us to look at as seriously dangerous. Which actually sounds more threatening: “Empress Catiz I of Amarr,” or “Kittens”? “Lord Consort Aldrith Newelle” or “Aldieboo”? Maybe it’s a matter of her impulse to treat the Amarr irreverently working in tension with her desire to drum up fear and hatred of that same religion).
She uses it, a few others adopt it … and here we are.
The Amarr, in general, take Nauplius a little more seriously (he’s intentionally murdered millions, after all), and often refer to him as “The Butcher.” He doesn’t at all like that nickname, though he seems aware of the horrifying nature of the stuff he’s done. I guess, maybe he feels like it drains his brutality of the meaning he sees in it.
Of course, to the rest of us, that’s kind of the point: directed as it is only by his own troubled mind, a thick, foul stew of Sabik and Amarr religious principles bubbling in a broth of pathologized ego and confirmation bias, it is, in fact, slaughter without meaning, butchery without purpose.
Empty, meaningless horror.