This article does plenty right but gets a few things wrong. Overlooks a few others. I'm going to hit on a few of these in order I see them.

"Avoid cipher cascades." I've pushed and successfully used cascades in highly assured work for years. Cryptographers talk down about it but "meet in the middle" is best attack they can cite. So, they're full of it & anyone who cascaded might have avoided many algorithm/mode breaks. My polymorphic cipher works as follows: three strong algorithms applied out of almost 10 potentials; algorithms are randomly selected with exception that each pass is a new algorithm; separate keys; separate, initial, counter values; process driven by a large, shared secret. Breaking it without the secret requires breaking all three and no cryptographer has proven otherwise despite massive speculation.

I'll briefly mention scrypt because it's ironically great advice. I asked cryptographers for over a decade to deliver a slow-by-design hash function that couldn't be sped up. They, for years on end, criticized me (see Schneier's blog comments) saying it was foolish and we just need to iterate a fast one. I expected problems and hackers delivered them. I had to homebrew a cryptosystem that input a regular HMAC scheme into another scheme: (a) generated a large, random array in memory, (b) did impossible to speed up operations on random parts of it, (c) iterated that excessively, and (d) finished with a proper HMAC. Array size always higher than GPU or FPGA onboard memory in case opponents used them. Eventually in a discussion, a Schneier commenter told me about scrypt and I finally got to ditch the inefficient homebrew. A true outlier in the crypto field.

Avoid RSA: bad advice for commercial if NSA is opponent. All his risks are true. NaCl is great and my default recommendation. Yet, he doesn't mention that NSA has another reason for pushing ECC: they own 26 patents on it that they license conditionally on the implementation details along with ability to restrict export. We know what NSA's goal for crypto is and therefore I avoid ECC commercially like the plague. I just used RSA implementations and constructions pre-made by experts with review by experts. Esp GPG, as NSA haven't even broken it. They use it internally, actually.

For asymmetric signatures, see above. All points apply. I'll just add that, for post-quantum, there's been tremendous process in Merkle signatures with things such as unlimited signatures. Their security just depends on a hash function, there's no known quantum attacks on them, and they're doing pretty good against classical attacks, too. So, I'm following and doing private R&D on standardizing Merkle signatures plus hardware to accelerate it on either end.

He says use OpenSSL and avoid MatrixSSL, PolarSSL, etc. He said some vague stuff about their quality. Problem: anyone following the git comments of OpenBSD team that tore through OpenSSL knows that IT WAS S*. It was about the worst quality code they've run into with so much complexity and potential to be exploited that the NSA would be proud of it. I'd be surprised if Matrix, Polar, etc are worse and less structured than that. If OpenSSL is really the best, then we're in a bad situation and need to fund a clean-slate design by experts like Galois and Altran-Praxis.

Although I'm focused on problematic points, his last piece of advice deserves special mention: use TLS. These protocols have proven difficult to implement properly. TLS and their ilk have had many problems along with massive effort to smash them. Against that backdrop, it's actually done pretty well and using it like he suggests is best option for COTS security. Medium to high assurance systems can always use variants custom-designed for that level. Most don't need that, though.