A cameramans harness will have a quick release handle much like on a parachute harness, therefore it is very quick for said person to exit the aircraft if they happen to survive the crash if they're not in their seat wearing their seatbelt (an unfortunate trade-off of achieving the task at hand vs risk). If someone's attached to the aircraft via a harness with no way of releasing themselves in a hurry other than via a carabiner that is connecting them, good luck getting out when the s*it hits the fan..
Furthermore the camera should be attached to the aircraft itself via a load rated strop/teather to stop it ending up going through someones' roof and landing on their dining room table in the middle of dinner. It won't act as an anchor on the cameraman that way.