...Or a time-traveling obsessive patriot from Earth, with copies of important paraphernalia. Sort of like John Gill with a time machine.
Stardate order helps us with, say, the Khan-knows-Chekov issue ("Catspaw" comes before "Space Seed"). Moving "Omega Glory" from its production slot to a later point in the timeline would be beneficial for a very similar reason: Galloway dies on Omega, yet the character is also seen in "Turnabout Intruder". Having "Omega Glory" take place after "Turnabout Intruder" is a fairly obvious solution without major downsides...
I always assumed the order of episodes was chronological order, thus Chekhov was on the Enterprise in Space Seed, we just didn't see him. (Which can be said whether or not we place Catspaw before it anyway
..).Anyhow it's interesting to consider the series in this way.