A hypothesis for discussion:
Charlie Hebdo is not about freedom of speech. It’s about the state monopoly on violence: “the right to use physical force is ascribed to other institutions or to individuals only to the extent to which the state permits it” (Max Weber, “Politics as a Vocation”). The caricaturists’ “freedom of speech” protects them from state suppression or punishment of their speech as speech. Because they were offended by what the Charlie Hebdo caricaturists drew, the murderers claimed the state’s “right to use physical force” as their own. Such vigilante justice is what should be condemned here; no defense of “freedom of speech” is necessary (or even appropriate?).