The pilot, Barton, is on a mission to land his Emergency Dispatch Ship on the planet Woden, where he intends to deliver a cargo of urgently-needed medical supplies. When he finds out that there's a stowaway on board the ship, Barton knows that his mission could be in serious jeopardy. Marilyn may just be one person, but there's only enough fuel aboard for the pilot and his load and so the rules are pretty clear: any stowaway must be ejected into space immediately.
What Barton wants to do more than anything else is his duty. He has wide experience as an EDS pilot, and clearly takes his job very seriously indeed. He's certainly not about to let human emotion get in the way of the cold, hard logical calculations he needs to make:
He was an EDS pilot, inured to the sight of death, long since accustomed to it and to viewing the dying of another man with an objective lack of emotion, and he had no choice in what he must do.