Heinlein was a Fascist?

I just finished rereading Robert A. Heinlein’s STARSHIP TROOPERS, and I was left with an odd question lingering. Blazoned on the cover of my paperback edition boast the words “controversial best seller!” Why is this book controversial?

Science Fiction is something like a game or thought-experiment played with the reader: the author invents a counterfactual premise but uses the props and setting of the real universe to make the counterfactual seem as likely as possible. The game is to draw out ...