Why should muxtape get to do something unethical when everyone else has to follow the rules? You're basically saying this is ok because no one knows about it. Is it ok for me to steal something from a store as long as no one catches me doing it?

Perhaps a better way of going about this would be to contact the muxtape developers directly, however like you said before, they already know about this.

Also, in this situation, the RIAA would not necessarily be doing anything unethical to shut down this site. They are hosting free music on the internet. Can you think of a more straightforward way to break copyright law?