I think Franz and friends really did not want to die in this world. People offering them truth about the gentile times being not 607 BCE was killing there heavenly buzz. Loyd Barry gave a talk in Australia in the 1980's saying that 607 BCE and 1914 was the most important doctrines for J.W.
That's why they went with double "generations" bullshit which really makes us as wacky as Mormons or Scientologists.