Yes, it was. It never really made much sense to begin with - so Plame is outed as a CIA agent, so what?
BUT...
Fitz isn't after the leaker and probably hasn't been for a very long time, perhaps since the beginning. He's after anyone who can remotely be accused of not cooperating with the investigation. And that's all he's after. And Libby fits the bill, and so will constitute the requisite hide tacked to the barn the Dems have been screaming for. Cruel business, politics.
I think you have nailed it, and so has Eva.
Libby, who wasn't the leaker, wasn't sufficiently forthcoming about not being the leaker, so he gets prosecuted, while the leaker gets a pass (as do Novak and Corn, who actually published the information).
Who told ARmitage?