The problem is the federal government in the schools, let alone their cafeterias, to begin with.
In large part, I agree with you. And if was handled locally, we could be certain that at least in some parts of the country our schools wouldn't be poisoning our kids.
But as long as the Department of Agriculture is publishing "dietary guidelines" that are primarily written by people on the payroll of the grain and edible oil industries, it doesn't much matter whether it's the federal government or a local school board mandating they they be followed.
The USDA shouldn't be issuing "dietary guidelines" for anything other than crops and livestock - not humans, and especially not school children - because the federal government has no business involved in K-12 education - period.