The fact that we are so very many, MANY orders of magnitude away from theoretically power-optimal computation
Who is talking about that? Both speed racer and brainiac CPUs are synchronous digital circuits designed using the same tools and methodologies that use non-reversible, non- energy recoverable circuit design. Your objection on this theoretical efficiency basis is groundless obstreperous criticism for the sake of being disagreeable.
It is like you jumping into a discussion of equivalencies between different ways to build steel suspension bridges and saying it is invalid because it doesn't consider how carbon nanotubes and artificial spider silk could in theory allow much more efficient structures.