Section 91A. The owner, operator or licensee of a radio or television station or network of such stations or the agent or servant of any such person shall not, in an action for slander or for publishing a libel, be held liable in damages for or on account of any defamatory matter uttered, broadcast, telecast or published over the radio or television facilities of any such station or network by any person whose utterance, broadcast, telecast or publication is not, under the provisions of any law of the United States or any regulation, ruling or order of the Federal Communications Commission, subject to censorship or control by such station or network.