The book is not satire. The movie loosely based on it is.

Remember in the movie when Professor Rasczak was teaching the class about service and the right to vote? The class room is a significant portion of the book and isn't satirical at all. Heinlein was dead serious about his views.

Walk softly and carry a big stick.

Heinlein absolutely loved the military. I highly doubt the book is satire. I just read it. Dude seems to think everything really would be chill. All the over the top sauce came from the movie but the movie left out the dope jump trooper suits.