I do feel for this family at losing such a beautiful little boy, however, if you don't keep your eyes on your children when shopping, etc., then you must face the consequences, 'specially if accidents such as this should happen.
If this rail had been faulty/loose & fell on him, then that would be another story - but he was swinging on it, (albeit innocently).
The 7 year old brat next door to us climbs all over his Dad's 4x4, hanging on the windscreen wipers, but his parents don't bat an eye lid. No doubt if he fell off & broke his neck, they would complain that the car body or wipers were at fault!
RIP the Somerfields little boy.