I could’ve used a more thorough explanation that it was intended to be a one-way trip and that anyone going on the trip wasn’t going to want to go home anyway, because of the substantial risk that society mostly collapses by the time a human can travel back at an acceleration that their bodies could handle, and the time dilation increasing both the risk and aging off any loved ones they might have. That way it makes it clearer that Grace’s strongest emotional connection back home is his students, who will be very different people, if they’ve even survived, and it makes sense that he wants to go back to teaching.

Although I’m also wondering about the pedagogy for teaching a species that doesn’t forget. The need to work through recall itself is less important, but it could be possible that teaching is more about training the problem solving and analytic skills using that body of knowledge.