I've sent hundreds of cars to body shops for bumper repairs.
If you use a dealer bumper repair guy, expect to pay 200 to 300 for the bumper, plus the replacement lens.
If you go to a body shop, expect to pay 1000, and, up to 3000 if it's a 'pearl' or 'metallic' white paint, and even more, if the trunk sheet metal edge (the metal the supports the bumper) is bent.
Also.... this is why he's got insurance. So. I'd just let them deal with it, and he's only out the deductible.