The revelation that the leaker was defense attorney Troy Ellerman might have gotten Williams and Fainaru-Wada off the hook, but it put the Chronicle on it. See, the problem is that the leaker was also the one who tried to get the case dismissed because of the leaks. He was, in effect, using the Chronicle to get the case thrown out. And not only did the Chron know that, they went back to him to get more information despite it all. In a blistering column in Slate, Jack Shafer says that in their actions, Williams and Fainaru-Wada were "sanctioning" the lawyer's "sleazy" moves. They were enablers, in other words.
Up until the leaker was discovered, other journalists were on board the Chronicle Love Train. Now, not so much. In a column in the LA Times, media critic Tim Rutten, castigates the Chron for subverting the importance of journalistic privilege for their own purposes. Says Rutten:
"Conspiring with somebody you know is actively perverting the administration of justice to your mutual advantage is a betrayal of the public interest whose protection is the only basis on which journalistic privilege of any sort has a right to assert itself.
See, here's the crux of the matter-- journalistic privilege is one of the bedrocks of a free press. But in order for journalists to be able to hold to it, they need the people's trust that they're doing it for all the right reasons and in ways that won't ultimately do harm. What the Chronicle is accused of is breaking that trust-- they claimed journalistic privilege for a guy who was using it for his own advantage. As Shafer points out, every sort of case like this features ulterior motives by the people involved, for both the leaker and reporter. It's just that one has to weigh whether the ulterior motives outweigh the benefits of the story. Like Plamegate, that might not necessarily be true of this story.