The chance of death at a given age oughtn't be a bell curve. The chance of me (33) dying at 60 are much higher than the chance of my coworker (65) dying at 60. There's a shear drop off at the age in question. After that point you have 0 chance of dying at the particular age, it's not a bell curve.
So I feel like I still don't understand what you're getting at in your example.
Do you want to understand? I'll try to help, but it seems like I'm using math terminology and concepts you're not familiar with, and I don't want to presume you're interested in learning math.
Sadly, we're not even talking about the meat of my point, you got stuck on the uncontroversial preface to my real point. My point was that Nautilus is wrong and maybe being sneaky by saying that aging accelerates near the end of life because the probability of dying is going up. That's not true, and the bowling analogy shows why.
Over time, the probability of pins being knocked over goes up. But you can't conclude that the bowling ball is accelerating. The author made an incorrect conclusion from the data to make his point. It might be intentionally misleading, or it might be a mistake, but it's nonetheless incorrect to suggest that an increase in the probability of death must have been caused by an increase in the rate of aging.
I'm not saying that the PDF of death by age should be a bell curve, I'm stating a fact. It already is a bell curve. Go look at the data. You're trying to argue against reality with logic. You're right, it doesn't have to be a bell curve. But it IS a bell curve.
Very few people die of old age at 55. Many people die of old age at 80. Very few people die of old age at 100, because there are very few people left. That's a bell curve. Does that make more sense?
So I feel like I still don't understand what you're getting at in your example.