All over the Muslim world, people are angry.
They have every right to express their anger
– as long as it is done nonviolently toward both persons and property and within the laws of the land –
...just as the maker of a trailer of the fake movie has the First-Amendment right to express his opinion
– as long as it is not fraudulently harmful or willfully offensive within the limits of freedom of speech in the United States.
The laws in the United States strongly protect the freedom of speech
– to the point of the absurdity that money has been deemed a form of speech by the Supreme Court decision in Citizens United v. Federal Elections Commission.
However, there are limits to freedom of speech that are based on the “harm principle” and the “offense principle,” i.e. limits on pornography, hate speech, and crying “fire” in a crowded theater when there is no fire.
In U.S. law, there is legal precedence for prohibiting “fighting words,” which cause those hearing the words to react with a “breach of the peace.” A stampede in a theater would qualify for that, as would an attack on an embassy, it would seem to me.