sounds like these 2 were banned from the restaurant for their behavior, not the amount they ate. The manager claims they were pushing and shoving others, and just being rude and uncivilized in general.
"The restaurant's owners said they were fed up with their lack of manners.
They accused the pair of pushing out other diners in their rush to get to the food.
Co-owner Peter Westgate said: "Like when the shark shuts its eyes before it feeds, they're like that. They just get to the buffet and whatever happens they just pile it in.
"They muck the buffet up for everyone, they push and shuffle people from the barbecue area and it's pretty sad really, because you can eat all you like over five-and-a-half hours - it's not an issue, you don't need to rush."
http://www.bbc.co.uk/news/uk-england-sussex-19817457