And likewise in this article, the church said the Stokes family was welcome to participate in the cubs and the parents could also volunteer.
As to leadership, though it’s rare, I had a non member Scout Master in my own ward a few years ago.
Well, even in those "rare" cases it's usually:
A non-Mormon husband married to a Mormon wife...and the church sees it as a way for him to interact with fellow Lds families; or
A non-Mormon relative of a Mormon family in the ward; or
They have exhausted other possibilities of getting somebody internally to lead in that capacity.
Usually instead of telling a non-Mormon who is applying for such a position, they will simply tell them all the positions are filled. And if a position is open, they'll approach a Mormon first to fill the position.
As far as I’m concerned, this is a religious charter organization of the BSA. They can say and do what they want to within their charter.