I find it kind of amusing that people think the Supreme Court can rule a federal agency unconstitutional.
Agencies exist because laws authorize them to exist. The Supreme Court decides only if LAWS are unconstitional. If the law is constitutional, then the court can consider if the agency's actions are authorized by law, or follow other laws (such as the Administrative Procedures Act).
In 1935, the Supreme Court ruled the National Industrial Recovery Act unconstitutional. It did not find the National Recovery Administration unconsitutional.
People consistently make the mistake of saying "the Court rules the NRA unconstitutional!" No, it didn't. I just smile and shake my head and correct the error quietly.