Well first of all the article you listed is inaccurate in the first paragraph, Jehovah's Witnesses are not banned in Russia at least not yet. And I cannot speak for what other people are doing but none are specifically assigned by either the Governing Body or by an entity used by the Governing Body to do that. And those individuals are subject to the laws of that land so if they do preach in a country where it is banned then they are in violation of that law. I know of a country committee member in Vietnam who is Australian, he and his wife do not go in service because preaching is banned in that country. The country does allow for meetings to take place legally and in the open so they attend meetings and assist witnesses in that way, but they do not preach.