If our constitutional freedom of speech allows burning the American flags and carrying insulting posters at military funerals, then it allows burning a bunch of books. Muslims are not special little snowflakes on US soil or in the US constitution.
They are simply responsible for their actions and we hold tem accountable even though we may not be able to punish them immediately if ever. If I murder you and then escape to a nation where I cannot be extradited to the USA, do you no longer hold me accountable? As you can see you point has no merit in discussing how WE handle free speech rights.
They are going to act out anyway. We have seen this time and again. It is not a slippery slope argument because it has already happened. This case is a prime example; acting in fear of prior bad acts on the part of muslim fundamentalists, a level of our government has acted to curb freedom of expression. This is not the first time people seeking to prevent possible reaction to protest have acted to curb First Amendment (and other Constitutional) rights. Look at all the gun control measures linked to mad-man mass killings. Look at all the violations of Fourth and Fifth Amendment rights linked to fear of the harms of drugs and terrorism.
The slope is heavily greased.
If I stop responding it doesn't mean I've conceded the point or agree with you. It only means I've made my point and I don't mind you having the last word. Please wait a few minutes before "quoting" me. I often correct errors for a minute or two after I post before the final product is ready.