State law doesn't require it likely, but it doesn't prohibit it. Lots of places require even volunteers that work in positions involving children to be background checked.
Frankly, unless there is a law that prohibits such background checks (unlikely), it matters NOT what excuse the organization makes for the check. If they say you must have one, you must have one or you can go elsewhere.
The "purpose" for the debacle is likely the perceived liability of allowing potential predators around children in activities they are sponsoring. You are not likely to dissuade them of that perception in this day and age.

