Doesn't look like there was a business to destroy in the first place. Just a scam that was, apparently, recognised as such by all the reviewers.
I just posted this as a great example of about the worst way to deal with customers I've ever seen. If the company isn't a scam they could have asked the customer what they could do to get rid of the rating. If it is a scam he could have just shut up, maybe posted a few fake positive reviews and left it at that. Instead he wrote an amateurish fake-lawyer letter threatening the customer angering a portion of the Internet against him.