This may take some time. I may have to explain multiple points separately.

Photons travel at c, which means they travel on paths with 0 proper delta-t (change in time) over all lengths. delta-proper-t? I'm talking about proper time.

A photon looks the same at all times which it exists. There is no way to determine the photon's age by observing some intrinsic property of the photon.

The age of anything is frame-dependent. Reference the twin paradox. A different amount of time passes for each twin, who observes (naively) that both are the same age - i.e. the same amount of time passed for one as the other; each observes their own time passing and knows that the other existed the whole time and none more or less.

Einstein strictly ruled out reference frames moving at c as non-inertial.

Here's a tricky one. You can't watch a photon age. Once you observe it, you destroy it. There is no frame in the universe in which you can see a photon "moving in time," inertial or not.