No, the Federal Service was not completely military --- that was just one small aspect of it --- as is noted in the novel, most people in the Federal Service are simply bureaucrats doing necessary government work (Skywatch is specifically mentioned --- a search of asteroids to determine which would have orbits which would intersect with that of earth). The protagonist's best friend who joins at the same time becomes a researcher on Pluto.
While I agree with your premise, it’s worth noting that much of the military is also “bureaucrats doing necessary government work.”
Which is why there is a rather marked divide between the "pencil-pushers" and "the tip of the spear".
That said, there are lots of instances of the clerk-typist being told to grab his rifle and fill out a billet for a patrol and similar things --- RH actually speaks to this and other similar, but broader concerns in _Starship Troopers_
True. Honestly, I thought it was a great film, and I’ve watched it a bunch of times. I thought it explored that topic quite well.