Ah sorry I missed that part of the argument. Yes, I agree that I can't imagine such a thing, because I don't think experience can be subdivided in that way. Anything a consciousness can perceive, it must experience.
I could however imagine a person whose brain perceived and reacted to the colour red in certain ways, but never became conscious of that perception, and merely experiences vision with all red things having the same qualia as another colour. It's quite a weird thing to imagine, but if you're trying to assert that it's impossible, I will do so to disagree.
> You can't imagine p-zombie, you imagine someone with attached label "There's darkness inside" (as Chalmers had put it).
Can you imagine a non-conscious rock? Or does the rock just have a similar label attached? If you believe one can imagine such a rock, then I can imagine such a human in the same way.
If not, then your imagination must be teeming with errant consciousnesses.