I think it's pretty obvious why. He's between a rock and a hard place. He was not beyond the reach of the US on allegations of spying releasing government secrets and a whole bunch of other laws he broke in order to become a whistleblower against the government's illicit programs --the only place which provided him refuge was Russia. No one else would take him. What do you expect, that he bite the cruel hand that feeds him? Be realistic.

PS. that's a very unwarranted swipe. Might as well request Obama to turn in his Nobel Peace Prize speaking of incongruencies.