I agree with everything I read in your book, but I also take issue with regard to your refusal to link the cosmic redshift to spacetime curvature. The problem is: If the electrons keep converting light energy into CMB, what keeps the universe in blance? The process needs to be more complete.
I think you fear reference to GTR indicates the Fiedman solution to an expanding universe, but the solution can have other interpretation. There is an escape velocity associtated wtih a gravtational field, for instance, but it's not actually a velocity. Similarly the Friedmann solution to Einstein's field equations need not apply to a finite universe; they can be restricted to conditons of an infinite cosmos. In this way we can rtain the equaiton of state of a pefect fluid characterized by a dimensionelss number in ration to pressure and energy density, and apply the enormous work of physicists to a more complete theory.
As Dirac pointed out, there seems to be ramarkable coinceidens between cosmic and atomic param eters. If we take the Hubble constant (71 km/s/Mpc) (as a velocity potential) to the distance equal to the diameter of the nucleus in the hydrogen atom, for instance, and divide it by light speed, it euqls the ration of G times the proton mass times the electron mass divided by the square of e, which is also equal to the ratio of the critical mass density of the observable universe and the mass density of the electron. Relating the first part to the last also renders a relation equating the gravitational force per surface area of the electron to the gravitational force per surface area of the observable universe.
These realtions are perceived as local conditions in the same way light speed is conditional to the structure of matter even though matter never obtains it.
The relations are also abstract and in need of mechanical interpretation. As of now, I will only say matter is absorbing, reflectting and emitting light in a way for a static-steady-state universe to maintain its state of dynamic equilibrium.