In the pilot movie "The Six Million Dollar Man" (1973) which preceded the TV series, Steve Austin was a "civilian member" of NASA who had walked on the moon, which justified his role as a test pilot. It was only in the second TV movie, "Wine, Women, and War" that he was changed to have the rank of Colonel. I have not read the Martin Caidin novels, but evidently he held the military rank and background in those.
Is there any evidence in writings about the pilot regarding what scenarios would be possible in future TV movies, shows (if they were already pitching it as a series) if he didn't have the military background? It seems as though they deemed it important in the initial pilot movie that Steve Austin was well-known as an astronaut, but was the cultural backdrop of the end of the Vietnam war part of their initial decision to shed the military connection?