Exactly, it wasn't about CP (in particular) at all, just pornography. Which makes it a really horrible ruling: at least with CP, you can use age limits, though there's still huge controversies about 1) pictures by parents of their kids doing stuff like taking a bath and 2) artwork/animation that isn't even photography and never involved any actual children.
Stewart's ruling was ridiculous: how is anyone supposed to know whether something is "pornographic" or not if it can just be determined by some judge arbitrarily and capriciously, and there's no objective standard whatsoever? They could just rule any picture of an unclothed person to be illegal, even if it's something medical in nature. Heck, they could even rule a medical diagram to be porn. Or anything they want, really.