Please say that the Hubbard book isn't appropriate for April so we can do away with it.
I have read it and it's not a satire or funny. It's SF plain and simple. Fantastic Fiction agrees with me.
http://www.fantasticfiction.co.uk/h/...aders-plan.htm. Overdrive also agrees.
http://search.overdrive.com/ti/e9788...on-earth-ebook Let's go for WorldCat as another source that says it's just SF.
http://www.worldcat.org/title/invade...=brief_results
So unless someone can find a definitive source that says it's a satire, it's not and never will be.