If one simply removes a hate speech preacher by deporting, arresting, or disappearing, their sudden absence leaves a martyr-like aura. The root source of funding funding it, if any, is also unexhausted and can send up new heads. So how about sue them instead, and continue to sue them while they continue to preach hate speech? When they lose a court case, the most civilised and well-defined and evidence-based of all fights, and as a consequence end up losing other peoples' money, they lose a lot more respect than they would if they disappeared. Let them preach, and let us sue.