Free speech is both paramount for its own sake and necessary for democracy. You cannot have a functional electoral democracy if the people already in power can decide what arguments and opinions everyone else can express. The viewpoint that censorship of expressions that those in power deem dangerous to democracy is justified to protect democracy is perhaps itself the viewpoint most dangerous to democracy. That doesn't mean it should be censored. It means it should be expressed by those who wish to express it and argued against by those who wish to argue against it, as with all viewpoints.