If you post stuff without permission, then sure, that ain't on.
But on Myspace, all you can do is link to songs posted by musicians. The *musicians* choose whether to post those songs online, and whether they're downloadable or whether you can only stream them. If the musicians don't want to make their stuff available, they don't have to. Their choice. And having made it freely available, they're not then in a position to say they don't like the rules.