I've seen this kind of thing before, but at Barnes & Noble it has always turned out to be a customer prank rather than something condoned by store management. It's sort of like when I found about a dozen bibles in a Fiction display at my own local B&N one time - the manager almost hyperventilated when she saw them there while rather loudly explaining to me that customers sometimes used her displays to make points of their own.
Found this on Twitter feed of @robbymyers who believes the book display reflects a liberal bias on the part of Barnes & Noble. I really doubt that's the case but I have seen similar things happen at independent bookstores that probably do reflect what Robbie is referring to here. I'm much more willing to laugh at this kind of thing (because it really is kind of funny) than to tolerate a bookstore burying deep in the stacks somewhere those books its management disagrees with - and that happens all the time.