How does this heater box retainer rod (J-hook) work?

What it appears to me is a pretty good attempt to seal the cowl to box, after the lower screw tore through the bottom of the box. All the repairguy would have needed is a wedge shaped stick of wood to finish the job.After the box is hung and the hanger installed, just slide the stick of wood through that lower loop until it tensions the box against the foam seal at the top. Then its business as usual. It would have saved the owner a considerable amount of cash VS a box replacement or repair.