The examples which you cite -- and which were deplorable errors in judgement -- occured during wars which endangered the Constitution. Had America lost either world war, the most likely result would have been the end of American democracy.

It is true, as you say, that one submarine sunk would not have lost the war but the logic was that enough acts of sabotage would indeed endanger the war effort.

In fact, in the quote that you gave from FDR's legal advisors the key words were "to preserve the national safety". This does not mean the safety of individuals but of the nation itself.

Individual safety has always come secondary to protection of the Constitution. For this reason, men were drafted and sent to die on the beaches of Iwo Jima and Normandy.

On a lesser scale, people who are known to have committed murder, and may well do so again, are set free when their arrests were the result of violation of the Constitution by the police. Here, too, the safety of the individuals they might someday kill is seen as secondary to the upholding of the Constitution.