The Founders did not agree. Blasphemy laws were routine in those times (until recent times, actually), as were obscenity laws, as were any number of local and state ordinances against loitering and incitement to riot. It's always been understood in America that public disorderbut not political speechhas its legitimate limits. The reason is that there's no freedom without public order. Libertarianism, taken to its anarchic extreme, never founded a surviving state.
I don't see what Federal law should have to do with this case anyway. The whole principle behind the Bill of Rights is that Congress shall pass no law. It purposely leaves the states free to pass such laws. If you don't like Cape Girardeau or MIssouri, you can move, and make the towns and states compete for your presence. The progressive Reds don't like this genuine diversity of custom. They want to enforce their hellish form of "universal diversity," where everyone is forced to confront Leftists burning flags and being obscene, and union thugs threatening businesses where they never worked. Leftist assaults on public space aren't freedomthey're totalitarianism.
You don't get to pick and choose parts of the Constitution that suit you and ignore other parts that stop you from doing what you want. That is the Liberal/Progressives ploy.
Amendment XThe powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
Free Speech is covered in the First Amendment. The First Amendment recognizes the right and by the passage of that Amendment the Government of the United States has the power to protect that Right. Thus the Tenth Amendment states that any powers "NOT" delegated to the Government of the United States nor prohibited by them are reserved to the States. Thus the States have no right to limit Free Speech because the Fed Gov has the power to protect it AND is ordered to do so by the law of the land!
This is 1st year civics stuff. Might I suggest you sign up for a refresher course.