I agree you can’t blame everything on the NSA.
But.. Cain is someone both the Democrats and the GOP-e.. did NOT want to face.
The Dems safely assumed Cain would have a tough and unlikely fight to the Nomination, his having zero electoral experience whatsoever. Romney’s people saw a genuine threat that could be bought off with a bribe to a past-use-by-date broad. Occam’s Razor says it was Romney did the deed, not NSA.