In the early 1980s, while I was still a teenager, the supervisor at my summer job promulgated all manner of conspiracy literature, and believed every word of what he read. In addition to treatises regarding the Kennedy assassination and denials of the Holocaust, he had pamphlets and books about Nazi rocket bases in Antarctica (Neuschwabenland) and Nazi UFOs. This was a grown man in his early 40s, who served in the Marine Corps during the Vietnam War.
By no means stupid, he was, nonetheless, sufficiently conceited to believe he was more intellectually enlightened than the masses because of his appreciation for, and encyclopedic knowledge of, such revisionary pseudoscience.
The subject matter of Iron Sky, absurd though it may be, has a history of its own. Wikipedia (The last resource I would endorse) provides a brief overview:
http://en.wikipedia.org/wiki/Nazi_UFOs
Though I have a master's degree in cinema studies from NYU, I wouldn't dream of passing judgment on Iron Sky until I see it, which, most likely, will be never (being a German film, produced independently, international distribution is unlikely). Likewise, I won't pass judgement on its target audience. The ignorance present in the world today cannot be blamed exclusively on the intellectual and artistic poverty of present day cinema. Those seeds are sown elsewhere.
I have no idea what constitutes the archetypal "fanboy," nor what percentage of the population is comprised by this class of person. Consequently, I'm in no position to predict his likes, dislikes, or general knowledge. Furthermore, I don't care. As long as he can hold a job and pay his Social Security taxes, who does, right?
For those interested in the compromises inherent to movies based on history, I thoroughly recommend:
The Hollywood History of the World by George MacDonald Fraser (author of the "Flashman" novels) and Past Imperfect - History According to the Movies, Mark C. Carnes, General Editor.
Popular culture has always been a question of likes, dislikes, and loyalties. I've never seen an episode of "Seinfeld," but I just finished reading Kenneth Roberts' Northwest Passage, all 709 pages of it. Does this make my interests better than someone else's? Hardly. It just makes them individual.
Oh, and, it seems to me, a movie, described by the producers as a "Sci-Fi Comedy," is beyond critical reproach.
http://www.ironsky.net/site/