Are we sure he never completed it? Or are these just missing parts from the (pirated? preview?) online PDFs?
Because if that's it, then it was just two points he was making, 1. Null-terminated char arrays are "defective"/unsafe, and 2. Don't omit curly braces, for which he seems to have received a lot of backlash, even though those are quite valid points. I'm guessing it may have something to do with taking it up against the grandfathers of C and his rather ...hands-on writing style?
Critique 1. isn't actually that controversial, and does have merit[1], and 2. is a stylistic decision, that even John Carmack[2] would agree on.
[1]: https://news.ycombinator.com/item?id=20792938
[2]: See "Spacing" in https://kotaku.com/the-exceptional-beauty-of-doom-3s-source-...