Deadline reports that the actor has bailed on the movie, unable to come to an agreement with the surviving members of Queen over the tone of the movie—Cohen wanted something more adult and gritty, the band didn't—and they have the final say on the script and director. The last we heard about the movie back in May, Cohen's "Les Miserables" helmer was being sought, and before him, Stephen Frears was apparently close to helming the project while David Fincher's name was floated too. And presumably "The Queen" screenwriter Peter Morgan is still involved, but this kind of delay suggests there's even more work to be done.
While a couple of start dates had been tossed around at various times—spring was 2013 optimistically touted and passed—it looks like this one might be a while off. A new lead will have to found, and someone who is down with something of a bit more crowd-friendly version of the story.