If the review was “this restaurant is ok” I don’t think they got sick from eating bad food so your example is irrelevant. Also typically getting sick from restaurant food is a complaint for the health department, not yelp
Also, have you actually seen health departments around the world? Have you actually tried complaining to them? They often are corrupt and do nothing! Even where they're not corrupt, they still don't take sufficient punitive action. And do you think someone actually needs to fall sick in the first place if it can be avoided via reviews? What you're smoking, you only know.