The “buffer state” argument seems anachronistic and incomplete. After all, what does China need a “buffer state” against? In any case, why does China support the current kind of regime if it “could crush North Korea in a day just by cutting off food and fuel” rather than forcing them to evolve in the ways that China has since the early 1980s? Of course, ideas have lives of their own, so perhaps 'buffer state' thinking is alive and well in the Chinese government.
I seems to me that in order to biomedically target the aging process as opposed to the diseases of aging it would help to have a biologically compelling definition of aging process that that distinguishes it from the diseases of aging and that guides experimental research. That would seem to be a job well suited to an analytic philosopher.