All movement is relative, as there is no universal zero spot.
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.
Careful, somebody's going to call you a geocentrist, lol. Never mind what Einstein had to say upon the matter.