I don't know whether you read the article through, but he later has strong stances against some books with outdated or bad advice. Furthermore, he is well aware of the fact that C (and systems programming, and systems themselves) has changed over the years. In general, John Regehr (a professor, not a college teacher, mind you) is very knowledgeable of C, compilers and especially systems programming languages, memory safety and undefined behaviour. I would say that his words have some serious weight.
