There may be an issue with the performance of music itself, regardless of the origin & copyright status. If you think about it, SE have said that you can play music from this game, in this game. All you are doing is offering something already licensed to this product in a different style. By playing something not specifically associated with the game it could be an issue about it being classed as 'additional content' that SE hasn't informed the authorities of (for them to check & approve).

I know what I mean but it's very hard to put it in words. XD