[Paleo Conservative]

"If Killian wrote 2-3 memos to file for Bush, he would certainly have written at least one other memo for some of the hundreds of other officers who served under him. Where are those memos?"

exactly

On the other hand, GWB was the son of the losing US Senate candidate in Texas less than two years previously. It is quite possible his TANG commanding officer might keep more detailed records on him.

[AMDG&BVMH]

Yes, he had reason to do CYA memos on LT Bush, but the National Guard is a state organization and more than one officer in his command over the years likely had connection to some politico or higher level officer.

And/or there was some other reason for an MFR -- death of a soldier (sorry, I automatically say soldier - airman prob. has been changed to airperson ), scandal of somesort, whatever. Things come up when you are a commander, that you want to record your recollection of while it is still fresh in your mind.