Obviously a scam though, doesn't really matter about the C class driver admittingly liability to his insurers since he would be considered at fault anyway for going into the back of you.
HOWEVER, you are likely to be "at fault" for bumping the car in front, and the fact they got out claiming they had sore necks basically means that they'll be blaming you, insurance company pays for their made-up whiplash, etc.
He wouldn't be at fault at all. He managed to avoid running in to the back of them and was pushed in by the Merc.
