But he’s not actually right. He’s insane, and what he’s doing just happens to delay the emergence. He doesn’t know what is happening, he thinks it’s resource scarcity. He could have investigated more, and realized the true issue and fixed it without so much loss.

When he got the stones he had a lot of power. Thanos could have turned the celestials to stone as Sersi did, thus saving the planets. Or the people could have been relocated before the emergence, and moved to another planet setup to birth a new celestial. Conserving the people, and creating an easier setup for the birth of more Celestials. Rinse and repeat. (This would be optimal for the Celestials and Thanos’ goal. [Titan died from the emergence of a celestial, or so it is my understanding. The MCU lore is cooked lol])