Who crucified Shirley Sherrod?

My cousin Ed is a syndicated cartoonist and winner of Hunter's Aronson Award for Social Justice. Here's his view.

My father used to say it took two to produce a news story: one to report and write it, the other to tell him when to stop. He was trying to teach a lesson about deadlines, but his observation also illuminates the truth that reporters hardly ever know all there is to know about a story.

Journalistic judgment calls for knowing when you know enough. But if that’s so, is the corollary also true: must reporters and their editors also decide when they don’t know enough? Is there a point at which a news organization shouldn’t publish what it knows?