Bring me the head of Donald Rumsfeld

If it's Monday, then it must be time for Newsweek to darken my mailbox. The front cover has the rhetorical question "Is He to Blame?" over a picture of Donald Rumsfeld. At least over part of a picture of Donald Rumsfeld, as from about the bottom half of chin is cut off. (Maybe to make him look short and/or powerless?)
In it, Fareed Zakaria and others make a big deal that the Defense Department is not following the Geneva Convention on the treatment of prisoners captured in the War on Terror. My take on this is "So what?"
The Geneva Convention sets up rules for nations to follow to make the conduct of war more "humane", if there is such a thing. And that is a fine thing, as long as we are at war with other nations who are bound by the Convention also. What I don't get is that Fakaria and other think that this binds the U.S. in our conduct with nations or organizations who did not sign onto Geneva Convention or particularly follow any of it's tenets.
In other words, Al Queda and other terrorists don't have to follow the rules and we do. Sorry, but I don't think it works that way. The Geneva Convention covers the rules of war between nations are signatories. If a nation or organization does not want to play by those rules, then there is nothing legal or moral that says we have to either.