The anti-Dubya MSM figured out two days ago that the best they can do is make this into a he said/he said matter [a draw]. They figure the public will only focus on the headlines and will draw the conclusion that something dark and sinister happened at the WH, but the media hasn't been able to nail them on it.
The prosecutor can go either way: release enough info to exonnerate Rove et al...or issue an inconclusive report playing right into the MSM's angle.
(Of course, he could indict someone, too...but we don't know enough to go there yet.)
They're trying to put up a rear guard action to protect their retreating troops.