They would immediately try take legal action against the American administration through any and every international court available. Having been detained without sufficient evidence there is a case to answer, the US and their cohorts (let us not forget that several governments including ours in the UK have been shown to be complicit in rendition actions that deliberately circumvented international law) can't try ignore the issue with the "enemy combatants" and other such reasons without looking like complete hypocrites given how loud they shout when someone they care to defend is detained without what they consider to be sufficient evidence (Iran holding several naval officers for instance). Even more embarrassing: some of the people they are refusing to let go home to face/demand their own country's justice are American - they don't even want their own legal system anywhere near this.
tl;dr: Just letting them go would certainly not be cost free, financially or in terms of local and/or international reputation.
That doesn't make what's happening the right thing to do... Well, if we just summarily execute them, then we don't need to take care of them... It's the fiscally responsible thing to do. I mean, war crimes are war crimes.
I'm not arguing that it is right in any way - just that the "if we just X it won't require any cost/effort" was a slightly naive PoV. My wording may not have made that clear.
The interview in the story claims to be reported by the prisoner's lawyers. What prevents them from taking legal action now? What changes if their client is released?
By my understanding, their layers are pretty hamstrung. That they have them is something, but their arguments for presentation of evidence, fair trial, rights as stated in the Geneva convention, and so forth, are for the most part unsuccessful - usually falling to a simple response of "the national good" which comes back to the circular argument "present evidence of that risk to (inter)national interests", "we can't do that, it would be a risk to (inter)national interests".
Right now they still have "enemy combatant status" and are not in a position where they can push their defence any further or be helped by their own governments and/or legal systems (if said systems would in fact help: some would, some wouldn't). If they were freed without charge then they have a case for unfair detainment (where now any such claim will be replied to with "they haven't been charged yet, that might change") and if they were charged there would be something for them to try make a case against (where now it is someone's un-evidenced word against their's, neither side having much legal standing so the people holding the keys "win").
If they were sent home, very many of them would be instantly killed, imprisoned or worse. For many of them, Gitmo is probably a lot better than they'd be facing at home.
Let's not forget that this comment of yours is in a thread about a guy sitting in that very same place, _asking_ to get home whatever the price would be. So the whole article that spawned this thread shows a very different position.
That totally ignores my immediate 'citation needed' urges and my shock about this opinion.
And I responded to a comment which was simply saying "Just send them home". That can't be done for "them" all.
I believe there is a wide variation within those imprisoned: some are innocent and were captured by mistake or worse (e.g. rivals were turned in by jealous neighbours, or whatever), others are actually hardened fanatics. And it is very difficult to know who is what.
And since when is being a "hardened fanatic" a crime? As long as they're not otherwise engaged in criminally acting that out, who the fuck cares what they think? If there was any actually solid evidence for anything real against them, they wouldn't be in limbo, would they.
Then give them a choice to go home, and if they don't want to, grant them asylum in the US. There's no reason for them to be locked up in a quasi-jail just because it's unsafe for them to go home.
As far as I understand, this is quite a real problem: no country is willing to receive most of these prisoners, except countries to which the U.S. cannot reasonably send them. Public opinion in the U.S. is hostile towards accepting them as refugees. A few have been placed to Palau, because sending them home to China would be bad and Palau is in no position to refuse such a request. Is that fair? Hardly.
In the U.S., lots of people in principle like to close Gitmo but in practice want the prisoners go to somewhere else, not settle as their own neighbours.
They shouldn't be in any detention center – there is no legal reason to detain them.