So, from what I understood, they had a quantum system of two entangled photons, where one photon acted as a "clock", and the other photon acted as a "system". The quantum system had all possible states "encoded" in it and thus it was "frozen" (it didn't need to change because it already represented all possible states, makes sense). Measuring the clock photon would yield the value of time for the system photon, and changing the "measurement angle" (whatever that is) would yield value of different time (kind of like a cursor over values of `t`?).

It seems like it was just deliberately designed that way, and doesn't necessarily have anything to do with our time. Correct me if I'm wrong.