One reason, I think, is that whatever our differences with American liberals may be, conservatives understand that our argument with them is still within the family. The fighting is intense, but we’re all trying to figure out what it means to live in this country bequeathed to us by the American Revolution and the Enlightenment.
Well, the thugs haranguing us about the proper limits of free expression aren’t members of that tribe. They haven’t paid their dues.
Because the moral superiority of liberty is irrefutable, totalitarians often feel the need to wrap barbarism in the language of freedom. For example, North Korea calls itself the Democratic People’s Republic of Korea. Similarly, the Muslim Brotherhood stooge running Egypt doesn’t care about free speech or tolerance; he cares about his own theocratic will to power — and making Americans grovel.
There are more practical reasons not to allow our liberties to be held hostage to the bloodlust of a foreign mob, but underneath them all is the instinctual tribal refusal to let marauders tear down what we’ve built.