If he'd jump on the 'new light' response. Ask, Does "new light" excuse false prophecy?
"From a purely human viewpoint, it could appear that these developments could hardly take place before the generation of 1914 disappears from the scene. But fulfillment of all the foretold events affecting the generation of 1914 does not depend on comparatively slow human action. Jehovah's prophetic word through Jesus Christ is: 'This generation [of 1914] will by no means pass away until all things occur.' (Luke 21:32) And Jehovah, who is the source of inspired and unfailing prophecy, will bring about the fulfillment of his Son's words in a relatively short time.--Isaiah 46:9,10; 55:10,11."
--The Watchtower, May 15, 1984, pages 6-7
Note: The expression "[of 1914]" is in the original Watchtower text.
“‘However, the prophet who presumes to speak in my name a word that I have not commanded him to speak or who speaks in the name of other gods, that prophet must die. And in case you should say in your heart: “How shall we know the word that Jehovah has not spoken?” when the prophet speaks in the name of Jehovah and the word does not occur or come true, that is the word that Jehovah did not speak. With presumptuousness the prophet spoke it. You must not get frightened at him.’"--New World Translation of the Holy Scriptures - Deuteronomy 18:20-22.