Depends what you mean by avoiding death. We all avoid death, some are just more successful than others (for reasons of luck or lifestyle). If they were arguing that it is unethical to, say, live for 150 years, because of overpopulation, then I disagree. There are two ways to slow population growth (mathematically speaking). Limit the number of children per mother, or have children later in life. Both have the same effect on growth. if nobody had children until, say, age 40 or 50, which isn't really safe right now, then there would be no problem at all (winning arguments with math is always the best route). As for whether you'd want to live to 150, I would say that there's no problem, so long as your quality of life is good. If you still get decrepit around 80 or 90, then it's not really an attractive option.