I think if he had argued that consciousness was a "transitional power source for intelligent behavior" it would all be cleaner. It is and was useful, but eventually becomes a bottleneck.
That reminds me of a Philip K Dick short story along those lines, The Golden Man. It's about a good-looking mutant who has no verbal abilities, but can see all possible outcomes up to a point in the future. He breaks free of containment, uses his ability to seduce women (also to escape), and in the end, the govt officials tasked with capturing him lament that he might be the end of the human race, if he has children with his ability.
It's not about consciousness, but the story definitely supposes that evolution can jettison intelligence if a better ability came along.