The Americans could simply be stubbornly refusing to admit making a mistake on their end--if for no other reason than to avoid getting caught up in a similar payout. Buying off terror suspects, even exonerated ones, won't play well in the press or electorate there.
Or maybe, just maybe, there's still good reason to keep an eye on him.
Being not guilty of X doesn't mean being innocent of Y.
This has been another edition of "Simple answers to simple questions."
AFTERSNARK: Unlike dissonance and disrespect's "Loyalist," Glenn Greenwald is not a moron.