" The crime of maliciously, voluntarily, and willfully setting fire to the building, buildings, or other property of another person or of burning one's own property for an improper purpose, as to collect insurance."
You are wrong when it comes to burning flags... It doesn't matter what state or local law says about burning/arson. Under federal law, the proper way to dispose of a flag is to burn it. Federal law trumps state law...
What you meant to say was ''Under federal law, the proper way to dispose of a the flag of the United States is to burn it.'' Your formulation would include criminal penalties for burning ANY flag, which is simply risible.
At law, burning the flag of the United States falls under 18 USC 700, and is a separate misdemeanor punishable by a fine of up to $1000 and/or 1 year in prison.
Does that apply to the flag of a foreign country on American soil?