In reply to Fatboy:
I have never heard of an insurance company X-raying a bike frame following a collision.
It isn't worth the hassle.
Most, if not all, will accept a report from a recognised bike shop. (or two)
If he has the x-rays it is down to you to make a choice.
If there is no damage, why did he get a new one?
Personally I wouldn't go near a crashed carbon frame.