Every democracy has limitations on who can vote. At one time it was only white male landowners, and when the book was written (1959) Jim Crow laws were still in force. Compared to that, giving the vote to everyone who does government service seems almost progressive.
How so? I don't remember him writing much about civilian society, just the impression that it was a liberal democracy.
I think it might *seem* fascist because the book is all about an enlistee in the military, where actual fascism is treating everyone like they're in the military.