Not so fast. No such thing would happen. No one will eat there, so no one is going to get sick. Furthermore, this restaurant won't be around long. And where would this person get his restaurant supplies? I'd imagine few if any would sell napkins or utensils to this restaurant.
No government whatsoever is needed to stop such a restaurant. I'm sure it just irks you that the restaurant would fail and close without government intervention, but its true.
How do you know that? Again, this is libertarianism on show here. You guys believe that people are naturally good. "Who in the world would eat another person?" Did you see that story from a month or so back, out of Germany, where two (gay) men got together, and one agreed to be killed and eaten by the other. Before the one killed the other, they both ate the soon-to-be-executed man's penis together.
There is no level to which people will not stoop. All you need to know about human nature is that the Roman Coliseum existed. For seven hundred years, millions of people watched other people get impaled, burned, chopped to pieces, mauled by lions, etc. for their own viewing pleasure. Seven hundred years that went on until the Christians shut it down.
Don't be so sure that the Gunga Diner wouldn't be a success...