I was considering a rebuttal to this ATM idea, and realized that the argument appears to apply just as well to the standard cosmological model.
The crux of my question is how to resolve the apparent conflict between the following three principles:
1) Space-time is isotropic in space.
2) Space-time is evolving in time.
3) There is no preferred frame of reference.
Essentially, the evolution of space allows the photon density to form a local clock at each point in space. If this clock is isotropic in some reference frame, then the photon density age of the universe forms a global clock in this frame.
If an observer is moving relative to this isotropic frame, however, there would now be a gradient in the photon density along the direction of the boost. But this means the new frame is not isotropic, meaning that the original frame is a preferred frame of reference.
Where is my mistake in reasoning? Is this the CMBR frame?