Over-simply, because they do not want to indicate that their site is about those pages, for whatever reason.
In practice, I'm not entirely sure but it looks like it's quite old since those pages don't seem to exist anymore, even as folders which don't exist as pages in themselves, and they aren't 301-redirected to the current relevant pages.
In fact, they're all 404's. So perhaps they used to be pages, were deleted, and kept being crawled which made their site look crap (because of the 404's). Now they could use 301's, but I assume that the reason they didn't is because they might want to restructure the site in the future and re-use those pages. They don't use 302's because 302's are unreliable and freaky.
