Although the point here is that the guy did not get what he paid for, your arguments about the pump being adequate (apart from being completely beside the point) are totally flawed. I'm far from an expert, but even I can see holes in your logic.
165lph is at 73psi (iirc), meaning that with a 40psi base pressure, at 33psi boost the pump will flow 165lph. So, correct me if I'm wrong, at more sane boost levels the pump will flow less than 165lph. Although 165lph may be enough in itself, this is the pump's max/highest efficiency rating, and it's quite possible that it won't supply enough fuel at (say) 15psi above base to stop his engine from going bang.
But as has been said countless times now, the point here is NOT whether what you supplied is 'adequate', it's the fact that you sold an item that didn't match its description. It'd be like me selling you a GTR, and you got a GTSt with a GTR kit and couple of bolt-ons - they look pretty much the same, they (apparently) perform pretty closely, but it's not what you paid for.