The whole idea is that an agent can fully understand, model, predict, manipulate, and derive all relevant facts that could affect which actions lead to how many paperclips, regarding happiness, without having a pleasure-pain architecture.

Let's say the paperclipper reaches the point where it considers making people suffer for the sake of paperclipping. DP's point seems to be that either it fully understands suffering--in which case, it realies that inflicing suffering is wrong --or it it doesn't fully understand. He sees a conflict between superintelligence and ruthlessness -- as a moral realist/cognitivist would

he paperclipper can fully understand how your workspace is modeling happiness and know exactly how much you would want happiness and why you write papers about the apparent ineffability of happiness, without being happy itself or at all sympathetic toward you

is that full understanding.?.

But if you take knowledge in the powerful-intelligence-relevant sense where to accurately represent the universe is to narrow down its possible states under some correspondence theory of truth, and to well model is to be able to efficiently predict, then I am not barred from understanding how the paperclip maximizer works by virtue of not having any internal instructions which tell me to only make paperclips, and it's not barred by its lack of pleasure-pain architecture from fully representing and efficiently reasoning about the exact cognitive architecture which makes you want to be happy and write sentences about the ineffable compellingness of happiness. There is nothing left for it to understand.

ETA: Unless there is -- eg. what qualiaphiles are always banging on about; what it feels like. That the clipper can conjectures that are true by correspondence , that it can narrow down possible universes, that it can predict, are all necessary criteria for full understanding. It is not clear that they are sufficient. Clippy may be able to figure out an organisms response to pain on a basis of "stimulus A produces response B", but is that enough to tell it that pain hurts ? (We can make guesses about that sort of thing in non-human organisms, but that may be more to do with our own familiarity with pain, and less to do with acts of superintelligence). And if Clippy can't know that pain hurts, would Clippy be able to work out that Hurting People is Wrong?

further edit; To put it another way, what is there to be moral about in a qualia-free universe?