Steven F. Savitt takes a "representation of the rate of time's passing", without a second dimension of time, to be the relative coordinate times of relatively moving frames of reference, if I understand it correctly.
That is one meaning of the rate of coordinate time, but, to me, leaves open the question of the rate of coordinated (demarked) time to the absolute or qualitative temporal flow of now(s). In this sense, one always has 1 c-second per 1 q-second, independently of which object instantiates it. Nevertheless, the c-seconds of different frames of reference can be coorelated in the universe the way their respective q-seconds cannot. See previous posts.
I keep coming back to the astronaut whose clocks are behind ours on returning from Alpha Centauri. For the whole trip, we experienced absolute time. Therefore, for the whole trip, the astronaut experienced his absolute time.
How Fast Time Passes
Steven F. Savitt1
Department of Philosophy
University of British Columbia