Children in Picket Line

New Mexico
As I walked through the Postal Workers picket line, I saw two children who looked about 10 years old, carrying signs and yelling out "We damand respect". I called a television station to see if they knew if this was legal, being that the kids have nothing to do with the post office, and is it legal for a parent to have his kids in a picket line to help with the cause? The newswoman told me it was freedom of speech, and they can do whatever they want. Is this true?

[I AM ALWAYS LIABLE]

My response:

Yes. Even children have Constitutional rights, and First Amendment protection of Freedom of Speach. And besides, walking around is good exercise, and keeps their little lungs in shape.

IAAL