"Men did not make the earth ... it is the value of the improvement only, and not the earth itself, that is individual property... Every proprietor owes to the community a ground rent for the land which he holds." -- Thomas Paine, Agrarian Justice
Where is the evidence that this information will harm the American people? If by harm you mean liberate and inform, then perhaps.
If it harms the government, it is their own doing. No government, especially no American government, should engage in actions that, if brought to light, would undermine its image, credibility, and security.
It is incredibly foolish for the United States government to be forming secret courts and passing laws behind the backs of the people. Yes, the details of these actions being released will harm the government and they damn well deserve it for secretly twisting the law of the land to their own agenda by bypassing the legitimate branches of government.
I'd like to add that this almost certainly wouldn't have happened if we hadn't been at war for the past twelve years. No country benefits from an extended war.