Actually a nuclear explosion on the moon does send a pretty clear message about who the king of the hill really is.
I think it sends a message of another kind. God gives wisom and somehow we try to use it in the wrong way. This would have been soooo wrong.
Maybe the concept was that the Soviets would see us attacking the moon for no discernable reason, and conclude that we were so deranged, that they should just stay very far away from us.