Since your friend has been an active witness since the 70s, he should remember chapter 25 in the "Revelation Its Grand Climax At Hand!"(2006) book. The "two witnesses" are discussed in chapter 25 of the above book.
Rev.11:3 And I will cause my two witnesses to prophesy a thousand two hundred and sixty days dressed in sackcloth.
Since Jehovah's Witnesses are not Prophets, according to their own words. They are not inspired, and need to make corrections about their teachings,1914 generation, Rutherford with 1925, and "Children". Jehovah's Witnesses do claim to be "Prophets". Meaning they talk about their interpretation of Bible prophecy and when it does not come true they receive "new light". So Prophet and "Prophet" are two differant meanings in Wt. world.
By their own words it is not scriptural to apply the "two witnesses" to Jehovah's Witnesses because they have not been a true prophet of God. You have to be accurate all the time to reach the catagory "true prophet of God".