As I posted at Interference: It's called diversion. U2 want to make the announcement for the new album during the Super Bowl, not now. By attaching this song to RED (for the moment), as opposed to the new album, they can save the announcement until the actual Super Bowl, even if this song is also the lead single of the new album. They are killing two birds with one stone, and also creating confusion (and buzz) in the process. It's brilliant, actually.