Is it ethical for a retired officer to run for public office, and use comments from his OER as endorsements from the reporting seniors?

Sure. It speaks to his/her character and ability. Were an opponent to discover the OER/NCOER with derogatory remarks that opponent might use it against the veteran so ... its use is valid.

What office??? He is retired. I suppose the issues are a better platform to run on, but a little self-promotion isn't too far afield in today's political circus.

Maj Walt Stachowicz Generalizations or excerpts tastefully done could be OK. Citing his general success in the military would be much more discrete and correct IMO.