I think that was a point yhe author was trying to make; that velocity is always relative to something else. The theory that Cosmic Background Radiation (CBR) can show a center of the universe that gives a reference point was made and used for some of the velocities cited. But, CBR is just a theory.
Au contraire, it is a very simply observed and reported fact, famously seen by experimenters who were not even looking for it, even though there were those who WERE looking for it, just a few miles away, albeit with inferior equipment. Such is fate.