Sorry about that 16 months of your life; here's a pair of sneakers
There will be many more of these stories. As people begin walking out of Gitmo and the other terror war jails, blinking and trying to figure out if what they just went through was real, we'll hear over and over again how they were detained on some tip, hint, or clue that would prove to be worthless; how their interrogators first thought they'd caught some terror kingpin, only to lose interest when they realized their prisoner was a foot soldier at best, just an unlucky farmer at worst; how there were fewer and fewer interrogations, but still they were not released, for months or years, until some day they were given a pair of white shoes (what an odd souvenir) and a letter saying they were not deemed a threat by the United States, and put on a plane, and told when it landed that they were free. (Read Emily Bazelon's Mother Jones story on tracking the families of detainees here, and her investigation of torture at Bagram--which also notes the peculiar white-shoe detail--here).
And the awful thing here is, even if you stipulate that maybe, after a bloody attack, it's conceivable that a government would arrest anyone it has reason to believe might be connected to that attack or planned future attacks; even if some people might consider it useful to interrogate those people in secret offshore prisons where they are kept in dungeons and humiliated or worse; even then, why, why keep them locked up for so long after you know for sure that you're not getting any intel out of them?