Ok, is this bait?
The astronauts really are weightless, in the sense that they do not experience the fictitious force called "gravity." Gravity, of course, is the fictitious force that corresponds to the real force exerted by the ground on the bottoms of our feet. That ground force accelerates us relative to a truly inertial trajectory (which is, of course, a geodesic).
(Gravity <--> ground pushing up) is a pair that is analogous to (centrifugal <--> centripetal).
Are you serious? I really can't tell. From a man who referenced Landau & Lifshitz and was aware of the Copenhagen interpretation of QM, this must be intended as a joke. On the other hand, the absurdity is expressed with such sophistication and eloquence without any hint of irony or sarcasm that some may think it is serious. So, forgive me if I belabor the obvious.
Gravity is as real as an apple (remember the Newton's apple story). Whether you are free falling off a cliff skiing or free falling in orbit (free falling = no forces other than gravity acting on the object), gravity is there. In the latter case, gravity provides the centripetal force for that orbital motion. The ground force is equally real. It stops you from accelerating into the center of the earth when you hit the ground. They are both real, present at the same time, independent of any frame of reference.