Look, if the Watchtower organization were really the "Truth," then it would be a righteous desire to share what they had. It's only when one proceeds from the asumption that the whole thing is a farce that it becomes contemptable to want to take it to others. And Jesus, before he ascended to Heaven, told his followers that many of them would be slain for the Gospel's sake. John was almost 100 years old when he wrote the book of Revelation. If someone had said, "He shouldn't be spending all that time writing; he's an old man!" The Gospel of John had not even been written when the book of Revelation was written, so he was far from finished when he was writing his apocalypse.
If I were a JW, I would face death with some trepidation. I don't like the idea of not existing after death or of being recreated at some future time. Most Christians, however, believe their spirits will not only live on after death, but that they'll be in a place far better than here on Earth. If atheists are correct, then what difference does anything make? Whether someone croaks in the middle of a door approach really only means the person died doing what they enjoyed.
Older pioneers might be better off going to nursing homes and other places where they can place Watchtower materials. The only problem would be is if Evangelical "Christians" happened to be right, in which case a vengeful God would be waiting to throw everyone but them into a burning and never-ending Hell.
So as people get closer to death, many feel a need to get closer to God. It surprises me that some people seem to feel that living for as long as possible is the only logical desire for the elderly.