So Cole doesn't know for certain if that's the path to finding purpose. But there are so few certainties in the world. 9S supposes he should have expected that. The only certainty is that if he goes home and fixes things, he will die. And if he goes home and doesn't and 2B dies... he won't be long in the world, either.

The world will be meaningless if she isn't there.

But if Cole thinks that he can find purpose from talking and listening to people here, then, "...I'll... I'll try."

Cole understands, a little, in a way the others can't. That's how they had gotten along during the ball, wasn't it? They're not like humans, so assured in their life and existence.