Well, Hazel is just flat wrong about infinity.
The infinite set between 0 and 1 is actually the same size as the infinite set between 0 and 2, so Hazel is technically incorrect.
(It is not easy to succinctly explain why this is, although this site does a reasonably good job—there, the example used is the set of positive integers being the same size as the set of all integers, but it’s the same principle.)
However, Van Houten is right* when he says that some infinities are bigger than other infinities. For instance, as proven by Cantor’s diagonal argument, the infinite set of real numbers is bigger than the infinite set of natural numbers.
So Hazel takes Van Houten’s correct observation and makes an intuitive but incorrect conclusion from it, albeit one that provides her with real and lasting comfort.
The idea there was that I liked that 16-year-olds could make—as they do—incorrect abstract conclusions about complex mathematics. But even if these conclusions are incorrect, they can provide real and lasting consolation. I felt like it would be too neat/tidy to have everything be correct; I wanted her to make incorrect inferences from Van Houten’s monologue that still guide her thinking in a correct/helpful direction.
*I am not a mathematician, but I tried my best to get this stuff right. I don’t mean ‘think’ in the sense that this is the kind of thing you’re allowed to have opinions about. You don’t get to have an opinion on whether .999… is equal to 1, for instance. It is equal to 1. People smarter than us have worked hard to figure this stuff out, and we owe it to them and to the universe to respect what they’ve figured out.