I don't know anything about "preppers" so I can't really comment substantively on the OP. I can only note first that occasional reader/viewers don't fit anything. Anybody who consumes the majority of zombie/apocalypse offerings on hand probably is getting something weird out of it. But are there many such people?
Second, what the OP cares to call "misanthropes" might not be so objectionable rephrased as someone who believes that human nature means the struggle for survival will be a bloody war of all against all. I think that the real objection is not to the views the OP imputed to those who are fanatically interested in this kind of literature/drama, but the assumption that these are false views generated by ignoble motives rather than reflecting a profound grasp of reality. I strongly suspect that quite a few people, including some in this thread, find the many, many zombie/apocalypse offerings to be so compelling because they embody a rational fear, even if in a fantastic guise.
Otherwise it's awfully hard to understand how so many people can agree that zombies demand less willing suspension of disbelief. Dead people walking are less likely than closed timelike curves in General Relativity, and it is silly to pretend otherwise. Perhaps what they really mean is familiar? But "faster than light" spaceships are just as familiar, which strongly suggests that's not correct either. And it can't be the human characters either. In the towering mountain of zombie apocalypses there are precious few people.
(Yes, people are in the occasional work, since nothing is perfect, not even perfectly bad. But we're talking about the fanatics who have eagerly tackled the whole bloody mountain. They
clearly are not pursuing the well-drawn characters who typify the literature.)
What we come down to, is that either the fanatic reader/viewer finds the bellum omnium contra omnes deeply satisfying (or it's merely the killing is thrilling?) or the masses of.....someone
embodied in the zombies and crazed mobs resonates powerfully with a deeply held personal fear. There is hypothetical third case where someone isn't paying any attention to anything and doesn't think about it. But any such person's opinion would be worthless. On anything.
The asides about stormtroopers or Firefly's neoConfederate sympathies don't help those offended by the OP, I'm afraid. The notion that anybody whose latent fascist sympathies are aroused by the coolness of the stormtroopers would obviously go around murdering people is easily the shakiest, most impractical and illogical notion offered in the thread!
No, such people would most likely just be armored in their indifference to imperial war against inferior peoples, blithely indifferent to the slaughter of endless war against, well, pretty much anyone who dares to be born different.
The Operative's adulation of Cap'n Mal is about as close as you can get to a fantasy of an uppity n--- admitting he's been wrong as you can get in something that doesn't actually have Klansmen and swastikas plastered all over it. There's nothing "shorn" about Firefly, the objectionableness is not just there, it is blatantly there, as one of the coolest moments.
PS The whole attitude that you can't criticize someone for taste is disingenuous, given that everyone knows that's exactly what you criticize porn for. Of course, criticizing people for that taste fits a conservative world view, whereas criticizing people for other kinds of supposed infractions, like contempt for humanity, does not.