It's a straw man -- overpopulation is not the only reason to be against anti-aging remedies. The so called "sacrifice" of death is necessary for progress -- death is a prime mover of dogma, nepotism, wealth, and many more. Humanity benefits immensely from the periodic refreshing of the old guard.
It's a question of whether you want a better life for yourself or for your children.
It's not the only, nor by a long stretch the best reason to be against "ending aging". Human culture fundamentally depends on death and the passage of time. Our myths, rituals, literature and sense of history depend on death. I may be an old romantic, but to me life without the sense of impermanence and transience would be an impoverished life indeed.
Furthermore, death comes at a huge cost of losing the accumulated knowledge of all those people.
Really, "cure aging" is the same as "cure cancer" or "cure diabetes". Disease prevention is just a shortsighted version of curing the problem of aging in general.
It's a question of whether you want a better life for yourself or for your children.