I must be missing something.
The "evidence" used to indict Libby for at least one count was a series of recollections made before the GJ about his discussion with Russert.
My read of those statements was that was describing his thought processes before the GJ - in which he was admittedly trying to deceive Russert - and *not* that he was trying to the GJ itself. It's possible you could read it either way, but that's precisely why it fails to be a solid charge.
I read the same thing into it that you did. It was an explanation of what he had said, not an attempt to mislead the GJ about his words. Unless there are other statements involved, it seems a real stretch to make this the basis for any kind of charge at all.