Unprotected from what? Do you understand 10 year olds run around in rain all the time and play?
He was made to stand against the wall. So he wasn't allowed to create heat from activity. We might have played in the rain at 10, but I doubt many of today's 10 year olds do.
I think if that had happened to your child you would not be so "understanding". 8>) At least I would hope so. Punishment is one thing. Jeopardizing a child's health is unacceptable.