If some business tells all of their best customers to post a review on Yelp, a site they had never used before, then they actually are straw reviews and worth nothing - and this business owner admits that. Case closed. Filter working perfectly.
This is not to say that the one bad review characterizes this man's business in any way. He probably just doesn't have a tech-savvy, hip clientele, and the first yelper he ran into may have been a spoiled curmudgeon. What offsets the damage is that since he isn't drawing from that hip clientele, the review is likely not driving away any significant business.
The best response would probably be to put a Yelp sign in some prominent space, which might trigger someone who is familiar with their business to add a few more reviews. If he gives good service, the preponderance will be good. Much better idea than calling for a favor from your affectionate regulars.
There is no right to a good reputation.