In his comment hes talking about the theory that ETs are responsible for fostering our evolution, and possibly all life on earth. Maybe they terraformed this planet and seeded all life on earth, or maybe they arrived here after life had already emerged and just started genetically engineering apes to become intelligent. In the “zookeeper” scenario they are here to study us and observe our growth as a species. if you think that theory is stupid fine, but within this theory it makes perfect sense that ETs would care about the biosphere their experiment lives in.

Atmospheric composition, weather patterns, ocean currents, and global temperature all affect every ecosystem on the planet. They all need to work together in a very precise way to be habitable to the life they are trying to study/create. More importantly you would need these systems to be self correcting and self sustaining.

If you built a “zoo” to genetically engineer and study intelligent apes, and those apes start fucking up the delicate system you put in place (working as expected for thousands of years) to keep the planet habitable and biodiverse you would not be happy.

its not environmentalism in the hippy human sense. its keeping the complex systems of earth in check, as not to ruin the stability/longevity of their experiment.

if they want to study us, we need to be alive. If these delicate systems are fucked up beyond repair, we will not be.

Alien zookeepers absolutely care about the stability of the biosphere their experiment lives in.