He's not wrong. Nell does find people infinitely more scary than natural things.

A submarine. She'd seen a picture in a book and one in a movie here on the train. "Oh. I can see that." She closed her eyes for a minute, imagining it. "Okay, yes, one big enough for hundreds of people.. Must be interesting to live that way."

Then she laughed. "Look what I'm talking about. We'uns live on a train that's moving through some sort of void thing."