If you want to live a long life, weight lifting is counterproductive, especially if you become very massive.
Instead, you want to be small, fit, and not eat much (which means not doing unnecessary exercise). For example, this paper discusses how caloric restriction extends life spans for rodents, primates, and humans across the board: http://www.sciencedirect.com/science/article/pii/S1568163716...
Living a long life isn't the goal. Living as long a life as you can while at optimal health is. Being a small runt who doesn't eat much and who is always sick isn't a very admirable goal. The inverse correlation with grip strength and all cause morbidity is likely related to people with strong grips are sitting at their desk with Captains of Crush grip exercisers. They are likely in the gym, doing deadlifts, working with physically demanding objects, etc.
Our push to extend life span has resulted in us being old, pathetic weaklings. A long life that has the last 20 years spent in a variety of sicknesses sounds awful.
Instead, you want to be small, fit, and not eat much (which means not doing unnecessary exercise). For example, this paper discusses how caloric restriction extends life spans for rodents, primates, and humans across the board: http://www.sciencedirect.com/science/article/pii/S1568163716...