What is you have a 6 year old kid sitting in school next to a 6 year old kid with a knife?
You would scream like hell, and probably want to fire the headmaster of the school?
6 year old has less control and more unpredictable than older kids.
Who packed the knife with the lunch? His mom? Now she comes back and complaint?
A rule is a rule. If there is all the flexibility, then there is no rule.
Most people don't think much. As long as their kids are not sitting next to the kid with the knife, they would scream and yell to destroy a school. They don't want no rules as long as their kids are not threaten.