Oh for crying out loud. Now Gus, Ed, and Roger were not performing
their duties as members of the military; they were rehearsing for the
Daytona 500. How silly of me.

They were performing their duties as members of NASA. It happens that, due
to the requirements for astronaut selection, that most, but not all, of the
early astronauts were active duty military test pilots on detached duty to
NASA. Two of the men who walked on the moon were civilians.