Maybe time preference is not quite the issue here. Older people have a peculiar scheme of long/short term individual/impartial preferences: since they won’t live much longer, it’s reasonable for them to discount their own future welfare at a higher rate—i.e., no sense in saving for old age anymore; but precisely because of their shorter life span, their self-interest may not weight so much when confronted with preferences for the welfare of others.
Maybe time preference is not quite the issue here. Older people have a peculiar scheme of long/short term individual/impartial preferences: since they won’t live much longer, it’s reasonable for them to discount their own future welfare at a higher rate—i.e., no sense in saving for old age anymore; but precisely because of their shorter life span, their self-interest may not weight so much when confronted with preferences for the welfare of others.