You either have free speech or you don't. The First Amendment is there to protect the right of the individual to voice his opinion AND to illustrate it through physical actions as well. You may not agree with it but it is his right to burn the flag in protest. Its what makes this country great.
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 disorder—but not political speech—has 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 freedom—they're totalitarianism.
Absolutely right....while I think the guys a jerk he has every right to be a jerk. Problem arises when legislators pass unconstitutional laws....like ones that restrict a constitutional amendment!!