That's not how RBN works. At all.
EVERYTHING that's uploaded has to be vetted by peer review and HMX's own QA. EVERY track that's uploaded *must* be copyrighted by the uploader --- i.e., if you don't own the rights, "your" song doesn't get released. Period. That goes for samples, too.
No way in hell are we gonna see "fan-made tracks" on RBN. Just original material. (And possibly parodies could be legally wrangled in -- that's still a gray area that hasn't been explored yet.)