Not everything is as meets the eye with engineering. Quick conclusions drawn about components simply based on observing their material or "wow, this is bendy" are often incorrect. He may think that the vacuum is cheap/weak, but he has no analysis (FEA, for example) to back it up.
Mike--I was pleasantly surprised by that impeller design, too! It appears to be a pretty advanced style designed for high-speed efficiency, very similar to that used in the Dyson digital motor or a turbocharger. Google pictures of an automotive turbocharger/turbocharger compressor wheel and you will find great similarities.