Hit and Runs...

[Blueface]

Blew up that picture to focus on area of damage on his car.
Absolutely no doubt that did not result from hitting your car.
Photo could be fooling me but he does not appear to have paint transfer. Appears from photo to be more like paint scraped exposing material of bumper in its form prior to having been refinished.
Don't see any impressions in the material that would invariably have resulted from metal compressing into it. There would have been some type of impression in the plastic for sure.
While photo appears clear as to what it is, the best way would be In person, to be able to tell for sure on whether paint transfer or scrape. For a layperson, real easy to do. Take wax or compound and buff. If it comes off, it was paint. If it doesn't come off, it is the material underneath.
I think you will buff for days and not remove anything off this one.