Agreed that not all years are equal, and the impacts of early deaths can be large.
For measuring N, I wonder how much of this is availability bias. I know a number of old people who have outlived half of their friends, as well as seeing a few friends lost early in life. My weak suspicion is that they would favor a lower N, just by more familiarity with death due to old age and a better idea of what old age deaths do to the culture / friend groups / family.
Google's announcement, Time magazine rather sensationalist headline.
In any case, it's nice to know that Google set its sights to "challenge ... aging and associated diseases". Apple's Tim Cook:
For too many of our friends and family, life has been cut short or the quality of their life is too often lacking. Art is one of the crazy ones who thinks it doesn’t have to be this way.
One more step towards "world optimization".