"While that is true, [the truth] may take a long time to come out and in the meantime, terrible damage can be wrought."
Okay, shall I personally appoint a Kommisar to vet all media before any publication is allowed to prevent the possibility that any falsehoods will be disseminated and thus terrible damage be wrought? Or shall we simply suppress all news that might cause terrible damage?
I don't think either is realistic, and far more terrible damage will be done by suppressing free speech than any damage free speech might do.
Speech which clearly causes major damage is not acceptable -- in our Constitution or in a reasonable society -- and such speech is not free. Libertarians may want to free the individual from all restraints, but most of us do not.