I'm going to briefly ignore the fact that we are probably the most overweight nation in the world and say the following:
1) I would think as far as buffets go, most restaurants should be pretty well off because even though most are advertised as "all you can eat", I would guesstimate that most people who do choose to go to those places don't eat 5 full plates. Most people make 1-2 trips to the buffet line... which sort of evens out with those that eat a lot more. I could be naiive, but do the majority of people seriously go to gorge and eat until their pants don't fit anymore? I'd hope not. I think the light eaters sort of even out with the heavy eaters.
(For all you super crazy fact-checkers, please note I did not say this is a fact, I am guesstimating, which means I do not have a source to quote, nor have I conducted a real life reasearch on how much people eat at buffets. It is my guess. If you have scientific evidence to prove that most adults and children go to CiCi's Pizza to eat until they can no longer move, feel free to post it and prove my GUESS wrong. If you have a different opinion on the majority of people's eating habits at buffets, feel free to express it. Thank you!)
2) I can sort of understand the restaurant's POV about wasting food because if one family there has 4 kids and they are throwing spaghetti and shrimp around the building, not only do the restaurant workers have to clean the mess, they have to cook more food for the patrons that are actually eating the food. If the owners want that as a rule of their own establishment they are free to do so, as long as it's posted so that people are aware of their policy and they are not surprised when they get the bill. If people see the policy and choose not to eat there because of it, they have the choice to leave.
3) With that being said, I don't think the restaurant should have charged the men for eating more UNLESS they had a policy in place that was visible before the men were charged. For example, if they had a "only 2 servings of crab legs per person, add'l plates $x extra" policy that the men were aware of, then I think that would have been OK, because then they would have been aware that anything more than that amount would cause them to incur additional charges. If the buffet was advertised as an "all you can eat" buffet, then I'd say they were wrong to charge those men more because if they can eat 10 plates of crab legs then more power to them.... the buffet was advertised as an all you can eat buffet.
(In my eyes, this would be no different than any other restaurant charging patrons for changing the side dish that comes with a meal or for additional salads, etc, but those charges are out there - usually on their menus - for us to know that if we choose to change our side it's going to cost us $2 extra)
So... that's what I think