It was an aprils fools joke from the company. I found the authors website, where he showcases it as part of his portfolio: https://mauricevanberkel.nl/portfolio-tag/easytoys/ And it is documented here also: https://www.adformatie.nl/merkstrategie/1-aprilgrappen-van-merken-professioneler-dan-ooit
The RHEL 7 book from OP is most certainly still relevant. For example, my department at work has not managed to switch over to the brand new RHEL 8 machines just yet.