You should have listed more of that quote. Directly above that President Obama said:
Now, finally, there remains the question of detainees at Guantanamo who cannot be prosecuted yet who pose a clear danger to the American people. And I have to be honest here -- this is the toughest single issue that we will face. We're going to exhaust every avenue that we have to prosecute those at Guantanamo who pose a danger to our country. But even when this process is complete, there may be a number of people who cannot be prosecuted for past crimes, in some cases because evidence may be tainted, but who nonetheless pose a threat to the security of the United States. Examples of that threat include people who've received extensive explosives training at al Qaeda training camps, or commanded Taliban troops in battle, or expressed their allegiance to Osama bin Laden, or otherwise made it clear that they want to kill Americans. These are people who, in effect, remain at war with the United States.
The ease/danger of a transition from a democracy to a totalitarian regime was something of which the Founders were aware. Our freedoms are protected precisely by a Constitutional framework which provides safeguards, like habeas corpus. President Obama is a Constitutional scholar, and acknowledges our bindings to it. Compare that with Bush who was rumored to say it's "just a piece of paper". There may be case by case issues which are difficult as well as debatable for any president to decide, but altering the legal framework in ways which diminish civil liberties and protections is dangerous, and can too easily lead a public that is not paying attention to a place they realize too late they don't want to be.
http://www.youtube.com/watch?v=Wmc60JmaLbE