The basic constitutionality of the act is not addressed because it is not even arguable. Congress can legislate under the Commerce Clause. The ONLY issue was one of delegation, can Congress delegate it's legislative authority to an executive-branch agency. Again, under fairly settled law, Congress can so long as it limits the discretion of the agency and provides the overall structure/guidance to the agency in the grant of delegation, and so long as the agency follows established principles of administrative law (due process, review and comment, etc).
The Commerce Clause was "fairly settled law" for 150 years before FDR screwed with it. Steak 'N Shake is older than the New Deal.
What was that again? ;)
Have the honesty to change your name to Daschle Man.