Having read some other Heinlein, I don’t think the man was capable of being pro-fascism (see The Moon is a Harsh Mistress and Stranger in a Strange Land). The book, in only my personal opinion, seemed more like a thought experiment, like most science fiction

Reminds me of the girl I dated who told me a story about how when she was young she thought her hamster was cold, so she put it in the microwave