Note that he didn't make any of these criticisms. What he did say is that there is little information about what the company's innovation is, and to public appearances what the company is doing is not novel. He then went on compare the company to another one with an impressive team of cryptographers behind it who developed an impressive, novel solution to the problem at hand. Further, he's made this point from a position of domain expertise in the field.
Frankly I don't think raising the spectre of famous "wrong" comments about Dropbox constitutes a meaningful response to his point. He outlined a substantive critique. In order for a criticism to be a middlebrow dismissal it has to be both middlebrow and dismissive. What you're responding to isn't, and doesn't fit the template you're invoking.