Understood. However, my comment had to do with establishing a fair policy rather than a over reacting to a large number of kids and imagined problems of the school. An out of hand lunch room is a result of poor supervision and discipline.
Children need discipline, but not an environment in which they are practically tied down every minute of the day.
What we don't know is the reasoning behind the rule. For example, have they had problems with fist fights, food fights, or other disruptive behavior in the lunchroom? Are there gangs at this school with the gangmembers congregating at lunch time? Rules like this are usually a result of past transgressions. I was in charge of 25 preteen boys last summer and by the end of it I was a fascist. It was like being in charge of a monkey cage at the zoo. Any thing that could be picked up would be used to whack someone else, and if it was light enough, flung at someone. Anyone with problems at home would come in and take it out on anyone smaller than them. I couldn't imagine riding herd on 260 of them, especially ones with whiney litigious parents.