I can see the tow truck hitting a bump and the cars front end bouncing enough to slam that 1/4 panel into the tire causing the damage. Can you file a claim with your insurance co and list the towing company as the responsible party? I dont think that would have happened at the mechanics shop.
I agree that it was most likely caused by the tow company. I don't have full coverage so I am not sure what I can do as far as an Insurance claim. I am going to talk to my Attorney today, as well as his son who happens to be a claims asjuster fo ran insurance company who has experience working with tow companies.