The the recommissioned officer who was the teacher was just combining two completely different characters from the book.

Why do the bugs have limited interstellar capabilities?

The movie definitely takes some of the fascist ideas from the books and amplifies them effectively. I think Heinlein was really asking a what if in the original book, similar to a lot of his other (also, 'problematic') work.

None of this implies a false flag.

If they wanted to amp up the fascism they could have used the opening of the book which was nuking the 'skinnies' a bug ally.