They may not be your best customers.. but they’re still customers. They are handing you money for your product.
From a PR standpoint there are better ways to handle this.
Up the price and buy more food. Use them. They are obviously fond of the restaurant.
Just because they’re customers doesn’t mean you want them to be customers. Some people are just no good, and the right way to handle them is to boot them and let it be public, let the people that abuse the system no they can’t there.
Normal restaurants make almost no money on food, the source of profit is drinks. Throw “all you can eat” on the sign and the amount of money you make on the food goes from almost zero to zero. Now you really need drinks.
Then you get two fat guys coming in, not getting drinks, and eat much more food than your average customer. Since they’re not getting drinks your potential for profit is gone, and then they eat a bunch more than normal people, now they’re taking money out of your pocket. Obviously they’re fond of the restaurant, who isn’t fond of getting more than they paid for. That doesn’t mean you should be fond of them. Kick em out. You’ll find you get more customers, because there’s a crowd of people in this world that see all you can eat places as where fat people go to be gross, and they don’t want to watch that. When word gets out you prefer customers that exercise self control you gain fans. And you lose the dump trucks.