Thanks for the bump, but I disagree with you here. The argument is made by the citation from Scalia. This may or may not be bad policy, but even though Scalia appears to agree that it is bad, as he said that has no weight at all on the question of whether or not it is Constitutional. Policy questions are not up to the courts, but instead are for the legislative and executive branches of government, and the people, not the courts.
On the question of Constitutional justification for the legislation, I am not a lawyer, but from the viewpoint of policy, I consider that it is certainly arguable that the cards might be of benefit to the national defense (even if only by making cases against terrorists easier to prosecute). This being the case the authority for this would be included in the Power to Make War.
...on the American People.