Indeed, if it were me, I'd let him take it to court, and argue the point that an inspection should've have happened BEFORE, and not after, agreeing a sale.A point that keeps coming up on bike forums (esp with newbies buying their first bike) is "if you're not sure what you're looking for, take a clued-up mate along" - to prevent this type of situation occuring - which is what your buyer should've done.
Ask for his mates qualifications, meter model serial No and current calibration certificate.