It serves no purpose, other than providing a place to put prisoners of war until such time as that war is declared to be terminated, you mean.
Gitmo is an outstanding place to put prisoners of war. If they escape, where are they going to go?
All of this is liberal bilge designed to hurt W. If they close Gitmo and put the prisoners elsewhere, they'll demonize elsewhere, and so on.
Under the Laws of Land Warfare, they can legally be summarily executed.