Totally dumb. They are insinuating that the witlesses are immune from dying. It is totally possible that the death was from smoking, from doing something totally stupid that the witlesses would not have allowed, or was a result of not being at a boasting session (because of blind dumb luck, they were in the path of trouble). However, there are plenty of causes of death that are independent of being a witless--I would estimate at least 99% of all deaths are not preventable by following the Filthful and Disgraceful Slavebugger.
And I have seen plenty of witlesses dying in their 50s and early 60s. They get into accidents while out in field circus, or they get persecuted. Their diets are atrocious--eating fast, good-tasting poison every single day for lunch, a TV dinner, a coffee and doughnuts for breakfast, and constant snacks in the car does not constitute a healthy diet. They don't regularly exercise. Their sleep patterns are even more atrocious because, between work, field circus, and boasting sessions it is always being disrupted. They are not mentally stimulated--after the first year or so, it is all boring. Their lives create depression because they are never allowed to have any fun, resulting in medication that usually ruins the liver. Those deaths would never have occurred if they were doing it their way--that is, each individual doing it their way, not the way of the Filthful and Disgraceful Slavebugger.