Right, light propagates as a constant value of speed in a vacuum. We can measure it and translate it into human symbolic language, the actual symbolic numbers are arbitrary values assigned by humans for convenience and accuracy. But time is not a constant, nor is it a thing, it is an abstract variable and completely dependent on the relative values of continued existence and duration of change of physical objects or change. In the absence of chronological existence or change there is no time at all. Universal Time started at the BB. Hence, Time is a scalar value, which can only move in a single direction (forward). https://www.quora.com/Is-time-a-scalar-or-a-vector?top_ans=89866170# Time is an abstract dimensionless mathematical object, which becomes expressed and quantified as a result of continuous chronological duration of physical existence and/or change. Time https://en.wikipedia.org/wiki/Time# Time does not exist as an independent plenum, but always as an emergent result (quantity) during chronological change. To me this scenario does not contradict any function of time, but does meet Occam's razor as a minimum requirement to satisfy the law of: Necessity and Sufficiency. IMO, spacetime = 3 necessary physical spatial dimensions + 1 sufficient abstract dimensionless temporal permission.