Assuming this is accurate, so what if Libby told Fleischer something that is "hush hush"? Last time I checked, telling someone something is "hush hush" doesn't mean "run out and blab this to the press."
As you say, assuming this is accurate, Fleischer seems to be the one who ignored the "hush hush" warning and went out to blab to the press. Of course Fitzgerald gave him immunity because that's not really what the case is about.