What's alarming is the unlawful way that the Obama administration carried out the swap. The law requires 30 days' notice to Congress before a Gitmo detainee is transferred or released. The White House has now brazenly flouted that requirement. And the precedent being set by Team Obama is problematic in the same ways as the executive-branch power grabs that happened during the Bush Administration. In fact, Senator Obama was a critic of the logic he has now shamelessly adopted. He decried signing statements, for example, but cites a signing statement of his own as if it is a defense against violating the plain text of what he signed.
The issue may not be merely statutory but actually Constitutional.