If we were to declare that in principle, a zombie is indistinguishable from a conscious person, then we would be saying that genuine consciousness is epiphenomenal in the ridiculous sense. That is just silly. So we could say instead that consciousness might be epiphenomenal in the Huxley sense: although there was some way of distinguishing zombies from real people (who knows, maybe zombies have green brains), the difference doesn't show up as a functional difference to observers. Equivalently, human bodies with green brains don't harbor observers, while other human bodies do. On this hypothesis, we would be able in principle to distinguish the inhabited bodies from the uninhabited bodies by checking for brain color. This is also silly, of course, and dangerously silly, for it echoes the sort of utterly unmotivated prejudices that have denied full personhood to people on the basis of the color of their skin. It is time to recognize the idea of the possibility of zombies for what it is: not a serious philosophical idea but a preposterous and ignoble relic of ancient prejudices. Maybe women aren't really conscious! Maybe Jews! What pernicious nonsense.
Or, as Helen aptly summarizes: "Epiphenomenalists can't mean what they say they mean, so clearly they mean something totally different. And doesn't that sound kinda sorta vaguely like a racist Nazi? So... yeah."
Nice fodder for a critical thinking course. Can you think of any comparably egregious passages from other published philosophical works?