Might not appear on HPI yet? A mate of mine bought a Merc C43AMG that was a Cat D for an apparent front end shunt, didn't show on HPI when he bought it but did when he came to sell it 2-3 months later. Similarly another mate of mine looked at an M3 convertible, was advertised as HPI clear to start but had pretty opbviously been damaged and repaired; not that well though. Couple of months later still for sale, the ad had changed to a Cat D repaired. Not sure if it takes time to appear on a HPI report...?
Or this one may have possibly recovered before the insurance paid out? He may just be advertising it as Stolen recovered to cover his own back. Wouldn't bother me at all, if it went cheap enough that is! Gotta wonder though!