Basically, Gitmo is a clusterfuck that no one man can fix. Too many people don't want to fix it in the first place, and those that do often have conflicting ideas about how they should. Saying that Obama "broke his promise" by not immediately closing the prison and releasing everyone who should be released (while conveniently only releasing innocents, suggesting that somehow we have 100% knowledge of who's innocent and who's guilty and we're just keeping people in prison camps because RAWR AMERICA IS EVIL) is fallaciously claiming that everything is up to the president.
Believing that the president has more power than expected or that he can somehow bully everyone into following him without causing more problems than it's worth is a very common belief, and one that cannot be held if you're planning on making any coherent statements about US politics.