The hesitation is all it really takes to spur Todd's mounting doubt into action. Neil doesn't need to ask him to go, he simply does so on his own.
He doesn't say anything, just heads for the door and shuts it softly behind him. He can get himself ready after Neil's done. And they'll make it through this. It can't be more than one day, right? Even two. As long as things go back to the way they're supposed to be, as long as they haven't lost everything they had somehow, to whatever void lay between worlds.