Yeah the most common example people like to pull out when they want to justify censoring someone’s speech is Justice Holmes’ nonsense “the right to freedom of speech does not include the right to shout ‘fire’ in a crowded cinema”. And it usually does get butchered into some version of that.
Of course the judge actually said “The most stringent protection of free speech would not protect a man in falsely shouting fire in a theatre and causing a panic.” [emphasis added]
So even in his case he basically identifies fraud…and not just any fraud, but fraud where arguable harm is done (i.e. “causing a panic”). (Granted it could technically be argued a “panic” was caused anytime someone’s heart rate increases a single bpm, but still…the fact that he included that caveat is telling.)
But to answer your initial question, sure, you could make a valid case that freedom of speech could be dangerous. Just like freedom of movement…or freedom to bear arms…or freedom to cook your own food. Living is pretty hazardous to your health. But obviously just because something can be dangerous, it doesn’t mean it should be banned. And it certainly doesn’t give anyone the authority to go around enforcing such a mandate.
The answer to this of course is quite simple…the property owner sets the rules. If you’re in my house, you can’t be setting things on fire, flags or otherwise. My house, I make the rules. You’re perfectly free to go to your property or the property of someone else who doesn’t mind you burning things. As long as you aren’t violating anyone’s rights, there’s no justification for aggressing upon you.
This would work for Mohammed/Muhommad/Muhammed/Mohommad portrayal, and nudity as well.
See here for resources on this kind of thing as well as many others in terms of free society.