I think it was a reference to the color scheme in the screen shot, not to the site itself. I find choices like dark blue and brown against black to be hard to read.
You've probably got a low-quality LCD with a bad color calibration, then, or else just a really bad contrast ratio or lots of glare. That color scheme doesn't seem to me to have any colors that would clash, even to colorblind and partially-colorblind people. Sure, it's a relatively low-contrast color scheme, but I think it would be generally harder to read if the contrast were really high. You shouldn't use much in the way of full-intensity colors when you have a black background.
It looks like it is a modified version of normal emacs highlighting for shell scripts to me; the colors are different from the defaults on my computer but not wildly so.
It's merely an accurate representation of the difficulty involved in writing bash scripts, as compared to just about everything else.