Even the best engine builders make mistakes.....
BUT if they dont stand behind what they build and if in fact they forgot to tighten the rods bolts they should give you full replacment.
Breaking your motor at the track is one thing,breaking it before you get to the track because of an "Oppps" is another..
I would have just sent the motor back and then worked it out before posting it on here for public bashing , at this point you have tried to hurt his reputation which is only warrented if he didnt want to make good.