Oh my god. Really?! You have to be kidding me. This phrase means: the color of static - gray and moving with flecks of random color. It has always meant this and always will. It’s inexcusable that a Wired writer doesn’t know this.
Even TVs that show the blue screen still show static for a second before the blue kicks in. I simply don’t believe that anyone really doesn’t know what static looks like, and this blue sky myth is just some kind of in-joke.