That is not what is happening at all.  The "state" is not making the kids go to this group, so it is a ridiculous notion that the "state" is deciding what is"right" for the kids.  The kids make the decision to join in the group.  It is the kids deciding what is right for them.  And joining the club helps them....it doesn't endanger them in the least.  Perhaps you can explain why you think it is detrimental to the kid to "leave the parents in the dark"?  

I suspect you wouldn't feel the same way if the school didn't tell you that your kid was in the "chess club".  Perhaps that is telling...