Basically, it's like he said we just woke up and realized that everyone is dead, so something must be wrong........DUH!
Yes, that is exactly what they are doing. It's their way of covering all bases. The 1914 generation teaching was long-term, but the term ran out. 1975 was fairly short-term to pay for WTS expansion of presses and multiply their members due to the panic. Now that years have passed and the doctrine has changed a few times, they look back at the 1914 generation and say "We were wrong. We must have been wrong because they are all dead."
This allows their members to accept their "other" teaching that only Watchtower admits it's mistakes and corrects it's path. "We are better than all other belief systems because we say when we are wrong." (Try to forget that it's decades afterward, or that we have blamed the members for misunderstanding us in the past.) "Christendom is all wrong and will never admit any of it, but we are almost never wrong and will always admit it."