The sentence immediately before the one you quoted:
> (A few years ago my students and I found a bug in the protocol, but Apple fixed it quickly — so I am very personally confident in their encryption.)
Which has a link to a post explaining more about it.
https://blog.cryptographyengineering.com/2016/03/21/attack-o...
Their bio on the website also states:
> I'm a cryptographer and professor at Johns Hopkins University. I've designed and analyzed cryptographic systems used in wireless networks, payment systems and digital content protection platforms. In my research I look at the various ways cryptography can be used to promote user privacy.
Maybe this person deserves the benefit of the doubt that they’re not just talking out of their ass and know at least a bit about the subject? Sure, have some dose of healthy skepticism, but make it informed.
