Actually, it only explains why Wilson--an open political enemy of the administration, was sent to Niger. It does not explain why anyone would "expose" her. The evidence to date is that her name came up when those who knew of the trip sought to explain it---not in an effort to undermine him, but to justify him.
I do agree the source most likely emanates from the CIA--or any cohorts at State (Plame was being moved over there and she could double as a source from either entity).
That makes sense. I was thinking that whoever appointed Wilson may have felt duped by Plame, but you are saying that it may have been more of a CYA thing.