My concern here is not the Free Speech issue, but the Film Makers, disregard for the Cast's safety and future. Putting People at risk, without consent, is pretty lame.
Yes it is, and it is not only lame but unconscionable. But I doubt that there is any controversy here whether it is unethical to depict people's words in dishonest ways. Most especially when it puts those people at risk without their consent. I don't think anybody will agree that is okay. But that is a different subject. (As is the fact that there are Muslims, probably most Muslims, who are not angry or murderous.)
But I keep pulling us back to the very heart of the paradox expressed in the OP. We now know that any words or graphic or portrayal perceived as insult to the Islamic prophet, Mohammed, will almost certainly result in violent retaliation from angry militant Muslims. So if we restrict free speech so as not to incur that often deadly violence, do the angry militant Muslims win? And how much could other freedoms be eroded if we give in to that kind of threat?
But that is balanced against the ethics of our free speech triggering violence that causes violence to people who had nothing at all to do with our speech.
Many here say that it is never the fault of those whose speech is used as the reason for the violence, but it is wholly the fault of those who commit it. That is hard to argue with.
At the same time, if we have the responsibility not to incite panic in a crowded theater, is there comparable responsibility not to incite anger that results in violence to innocent others who did not give consent to have their lives or property placed in danger?
Is there any honorable way to deal with this without giving in to threats from the angry Islamic world out there?