Butter, when consumed in large quantities (and oh yeah, kids will eat that shit all day) can make a person sick, or even kill them.
If you can limit it to one butter tab for each kid, that's cool.
I'm saying you cannot trust 1st graders to make their own food choices when it comes to unlimited quantities of fat/calorie rich foods. They'll drink a cup of syrup, stopping only to vomit. Kids do some nasty stuff, and will seriously mess themselves up with food.
So yes, you limit access of foods to children. That's nothing to do with govt intrusion.