Personally I doubt this story, but you are aware Barghouti is being held by Israel aren't you? If Israel wanted to release him for any reason, they'd release him. There's no quid pro quo required from America.
Israel might want to release him for purely strategic reasons but realizes that their domestic politics precludes them from doing this except under the smokescreen of "trading him for Pollard". The US benefits not at all from either end of this transaction.