Moreover people like Mill or Popper would argue people have a duty to engage every idea, because that's how the open society works.
The reduction of free speech to the first amendment and to State censorship is a modern american barbarism that is as absurd as it is baseless in either its historical roots or its application by any free judiciary, including the American one.
Telling people to shut up because their ideas are unpopular is and always will be illiberal.