You realize, any data on the internet is never gone, right?
Just because you wipe Yelp or clear the reviews, doesn't mean people didn't screenshot it, archive it, or cache it to search engines.
Check the deep web. After his review, others went and reviewed as well, soon it was a chain attacking the dishwater soup, and hair filled pasta, even reports of finding cut fingers in the salad.
Then, one day, all the reviews mysteriously vanished, all followed by the first reviewer dead.
Only, the reviews didn't stop there. Once they vanished and it was a murder, internet denizens took that as a challenge and it's spread all across tor web now. It just took statements and digging to find.