Sounds like a lose lose situation, but I think Steven is right, you'll probably lose more in the value of the car if you don't claim, than you would save with your no claims bonus. Why not try and stick it in an insurance form online and see what the difference is?
The ridiculous thing is that this is a company you're dealing with that claims it has insurance, not some random uninsured twat. Makes it even more enraging.
Also: Will he get prosecuted for driving without insurance?