If the terrorists were fighting under the Geneva convention, a country would lodge a protest and then you would have your problem solved Danny. Problem is no one wants to defend these scum and almost every one of them is captured in a country they are neither citizens nor residents of. They move country to country looking for a place to start trouble. You consider that a reason to be protected? And do you suppose we go to the UN and make claims Daniel Pearl wasn't protected? Of course not. Its an extra-national issue and the Geneva convent specifically does not apply to these affairs. They are considered equal to civil wars, which obviously do not abide by any rules of warfare.
As for the US, they are complaining about far more than just having the POWs on TV. Waving a white flag and making advances that suggest surrender and then starting to shoot and take hostages is not allowed under any treaties, but then again who expects an army under Saddam to do anything but bend and break rules? I don't think its so much crying over the POWs as it is to serve warning to a government that clearly has ignored or flaunted all semblance of international laws, despite their claims otherwise. If it weren't for their reputation as torturers I doubt you were have heard much of anything. After all if they can make killing and torturing their own citizens a regular part of a day in Baghdad, there is little doubt its the first thing that enters their mind when they capture even a handful of enemy soldiers.