Although I think the article as a whole is insightful, I really don't agree with the book analogy. Most of the time, one reads a book in a very linear fashion - left to right, top down, hopefully with little interruption. With code, I find myself having to jump around a lot more - to find where something has been declared, or to look up a subroutine, etc. This means there is a lot more searching for the relevant text in programming than in reading a book, and syntax highlighting helps my eyes identify these parts on a line or a block a lot more quickly.

However, I can see how turning off syntax highlighting could help one learn to keep more code in their head at once, so they don't have to jump around as much, but to me, it's not worth it.