Just as accurately, the above quote could read: Time dilation can be inferred from the observed fact of light's unique speed relative the absolute Geocentric reference frame.
That's right. Time dilation does not belong to relativity. I've posted a new YouTube video which explains how there are absolutely no Einsteinian concepts involved in time dilation. It is merely an a-relativistic theory which Einstein adopts for his own theory by declaring time dilation to be symmetric, or relative.
Time dilation can be derived exactly according to the same equations and diagrams used by relativists everywhere.
GPS corrections, particle accelerators, cosmic ray muons - all easily predicted from within an absolute Geocentric reference frame by the exact same method Einstein uses, with no sleight of hand and no mathematical corrections.