Free adults make decisions for children, and there is a long precedent( imo well justified ) of regulating decisions wrt to children: see vaccinations and mandatory schooling.
If anything, the federal government trying to ban it has only made it more popular than it was before.
It's not just raw milk - we're seeing this populist phenomena with everything. Anti-vax, moon landing is fake, QAnon, flat earth, crystals, sacred geometry, and on and on.
You tell people "The Establishment" serves one principal that's bad, but THEY serve an opposite principal, and you can get people to believe just about anything.
There's a whole culture and subsection of society who believes things purely because they think it's contrary to what "The Establishment" wants them to think. They reject anything with evidence or backed by institutions - that means medicine, food, policy.
This new-wave populism is fueled by our new communication technologies.
This is a problem with communication, but the medium is irrelevant. That people tend to dislike smart asses is a factor here.
The medium matters a lot. Any idiot can get on a soapbox now. Decentralized communication to the masses like never before.
You can see the spark of populism after each new medium. The printing press, radio, television - all accompanied with a populist movement of their time.
So you'd blame this on pastorization?