Looking at the individual level, most of us had close friends who had lost 30 years of potential life.
Suppose you could either extend the life of one close friend by 30 years, or the lives of all of your friends by 10 years. (Hopefully you have more than three friends.) Page is pointing out that the second could possibly be on the table, but it wouldn't be obvious because we're so used to treating rare serious diseases instead of making everyone a bit healthier or live a bit longer on the margins.
I fully agree with this point, and I fully agree with Page's goals. But I think there are things here that a simple total-years-of-potential-life-lost framework can not capture. As you might have guessed even from my first comment, this issue is very personal to me. Not long ago a good friend died after terrible suffering, leaving three young children behind. That's very sad, and I really don't know for what values of N could this be balanced in a utilitarian sense by lengthening the healthy old age of N of my friends with 10 years. Obviously, such trade-offs are taboo, but even if I try to force myself into some detached outside view, I still believe that number N must be large.
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".