Could Yelp be sued for this?

So a few days ago the review site “Yelp” decided that it would be a neato-keen idea to institute a new feature on their reviews of businesses: a button you could click that would plaster a “this business is racist” warning on your review. This was an astonishingly obvious avenue of abuse, and it appears that it has already been used to cause harm, both in the form of reputational damage as well as harassment and bullets. Recently some media outlets have found to their financial cost that falsely labeling people -ists and -phobes (and whatever the latest moral outrages are about) is not a good idea. So can Yelp be held to the same fire here? Could this be the sort of thing that brings their finances and existence crashing down?