There's a really interesting multi-part series called Brows Held High: Starship Troopers about the fundamental differences between Heinlein and Verhooven and what each was trying to say, between Heinlein's original and Verhooven's interpretation.

For what it's worth, I don't think Heinlein was fascist or even fascist-sympathetic. If you read more of his fiction and, my personal favorite, his non-fiction book Take Back Your Government, which is about how and why to get involved in democratic politics, you get a much more complete view of a really interesting guy. Some of his views were fair or even highly-progressive for their time. Some were weird and gross. But he's not one could simply stick a "Fuck That Fascist" pin in and walk away.