One of the first things I learned about in my color theory class was how colors can change how they appear depending what other colors they're next to. In fact, some colors will fight visually when placed next to (or on top of) one another. Saturated versions of red and blue were the first example given for that lesson. And that's exactly what the author ended up with here.

That said, there are some good tips in here for finding colors. I once asked a designer that I worked with and still highly admire, "how do you pick color palettes for things?" His suggestion was to start with a color you wouldn't expect, and then try to match colors to it. (He also recommended palette sites like those mentioned in the article for us beginner color people.) But the pick a color you wouldn't expect advice has worked well for me.