You will understand that I'm not privy to Apple's decisions: however my guess would be that they are concerned that you are using copyrighted music recordings. Without the written permission of the owners of both the music and the actual recording this would be a breach of copyright and is illegal, as well as (obviously) being forbidden by Apple's Terms of Use, and would result in your being removed from the iTunes Store. (This doesn't affect people who have already subscribed, as they are reading the feed directly and the Store is not involved.)