Yes it is for DIY purposes so The HASAWA as no place here. Neither would the HSE. It would have to be Trading Standards due to the incorrect fitting of the equipment.
Being a DIY project LOLER will have no jurisdiction. The only issue I can see is the installation has been done to a poor standard and that would be a Trading Standards issue not a LOLER one.
I would point him in the direction of the LOLER regulations, follow Doc Hudsons advice and walk away.
I've been responsible for safety and inspection of lifting equipment used for lighting rigs in theatres and the huge line array speaker stacks you see at concerts. I've also seen first hand what happens to a lighting grid when a chain hoist fails but the operator raising the grid was too busy chatting to a young lady...........
Being a DIY project LOLER will have no jurisdiction. The only issue I can see is the installation has been done to a poor standard and that would be a Trading Standards issue not a LOLER one.