his rep has been ruined which will lost likely mean he can't do any future work here.
False..
First of all having a feedback doesn't mean someone's reputation ruined. it is just a point of view of some individual while other (more then them) can have different (positive) point of view.. the only difference is those few feedback are visible while the other are not.
Second, no one's business life can or will stop just because of some negative feedback.