I think many here anyway can agree that Guantanomo Bay needs to be shutdown, but obviously won't be. What if later down the line we need to decide that the power has gotten out of control(if it hasn't already) and needs to be shut down. But can't because the terrorists win.
Establishing the truth of such an accusation is the very objective of due process. Thus, your question is internally inconsistent and circular. It literally cannot be answered.
Then what is the effective and ethical way of waging war against non-uniformed enemy? Arrest everyone then try them? What if it's not practical to do that?
If you're at war, you should only target enemy fighters in uniform, not civilians, and try to minimise civilian casualties at all times.
If you're not at war, people should be tried in open court and found guilty of crimes if they have committed them, not assassinated on suspicion, along with civilians nearby.
If you're proclaiming total war against anyone who is on a secret list, and leaving the power to decide in the hands of Obama, you are proclaiming the US a dictatorship where life and death rests in the hands of one man, and there is no recourse to justice before or after the killing. In the wrong hands and combined with total information awareness this would be a terrible power.
Terrorism is very difficult to counter, but I'd argue the way to do so is not to accept battle on the terrorists' terms - war amongst the people does not tend to end well for the government responsible.
The British policy on this, under which I grew up, was to treat such a scenario as a 'police action' wherein military presence was used to bring the situation to a point where the police could intervene.
Certainly troops operated checkpoints, patrolled streets and operated intelligence gathering, but all actions were in assistance to the constabulary. The ROE for line soldiers were extremely strict and even firing in self-defence was not automatically assured. A soldier could pin a suspect on the pavement but only a police officer could arrest him.
As a US citizen, do you approve of that? How about the US public?