at DSs school, which was buoilt for and is specific to children with ASD, they have a fixed open fenced area attached to each classroom ( like a permenant version of the one in the story).
It is to allow a child to safely leave the classroom if they are having sensory overload or need literally to cool off.
But that is for that specific purpose and sits within the spacious play areas and fields etc etc.
Perhaps the council saw this type of thing and misunderstood its purpose - thought that it was the whole story rather than a cool down area IYSWIM