I think this argument presupposes that biological life had found some healthy, deathless equilibrium; it's hard to imagine what that would look like, since we what we have is a system where death is a vital part of all that we see--it is required, in a most basic sense, to rejuvenate the greater system.

This isn't to say that "therefore we should all accept the inevitability of death"--just that we should consider carefully whether, in ending (or forestalling) death, we might improve the lot of the individual at the expense of the greater whole (society, other life on the planet, etc.).

Another thought--what if avoiding death ends up taking exponentially more resources as one gets older, and society becomes a superorganism oriented around keeping a small number of egos alive for as long as possible, where capacity to age becomes the ultimate expression of power?