Interesting twist to the case, but I can think of no Constitutional provision that allows Congress to bestow special status on the Boy Scouts.
They have bestowed such status on many groups in the past, the most notable is the US Olympic committee.
Did you know that that special act of Congress even bestowed a copyright to them on the name “Olympic,” and all of it’s derivatives?
I was a party to such a case involving them, and am intimately familiar in the ways that Congress can indeed create an act bestowing special status.
Again, today's generations have become so brainwashed by the ACLU that they think everything that gets done in the United States should be done by fiat of the Supreme Court. That's a recipe for oligarchy, not freedom nor a federal republic; and it's directly opposite to the original intent of the Founders who hammered out the Constitution in Philadelphia.
The states and localities are free to pass such laws as will benefit their local communities, and must only set them aside in the event that a successful constitutional challenge is made on the state or federal level. The U.S. Constitution is NOT meant to be a document to micromanage local areas.