Einstein said space is what you measure with a ruler and the only ruler used is the speed of light. ?

Given the basis of spacetime is the essential premise of Special Relativity that the speed of light is always measured as a constant. Logically then, if space expands, the speed of light would have to increase, in order to remain constant.

Two metrics of space are being derived from the same light. One based on the speed and one based on the spectrum. In this theory, the speed is still being used as the denominator, since it would be a "tired light" theory, if the speed were the numerator.

The presumption seems to be that light is basically a wavy line, that as it is stretched, becomes less wavy.

The math is muddled and the physics is awful. The waves are a function of the motion of the light.

It has been observed that while single spectrum light will only redshift due to recession, multi spectrum light packets will redshift over distance, as the higher frequencies dissipate faster.

The problem would be that it means we are sampling a wave front, not observing individual photons, which would raise interesting questions, as to whether quantization is fundamental, or an effect of measurement.