Hi Oz , your photo clearly shows that the magnetic material , the wire in this case , that is behind the coils , and opposite the magnets , is not moving with magnetic poles as the alternator spins.
So therefore the second disk on an axial flux machine , which sometimes does not have magnets on it , also does not have to spin .
I was sometimes questioning that premiss , that the second disk has to spin with the magnetic poles, because the magnetic flux will move along the path of the magnets energizing the coils as they pass. and probably could not care less if the second disk was moving or not..