I don't get his reasoning, he main critique is that bitcoin penetration/usage is way lower than "previously thought" or how the community makes it look like. I agree with that, but what does this say about possible future developments? if anything, I'd say "oh great, so I'm even more early adopter than I thought" or "there is way more room for growth than previously thought".
Only ~1.2M wallets have anything in them other than just dust or empty. Entities, merchants, and individual users can have more than one wallet. So do the extrapolation. Yep, we're still ridiculously early adopters.