 Why doesn't the crew throw Moran out of the airlock?
The plans were thrashed out very painstakingly, in formal conference on the space-yacht Nadine , with Moran present and allowed to take part in the discussion. From the viewpoint of the Nadine's ship's company, it was simply necessary to get rid of Moran. Moran observed these things from the control-room of the Nadine , then approaching the world on planetary drive. With clearance-papers in order, they could land unquestioned at any other space-port and take off again—provided the other space-port was one they had clearance for. Without rigid control of space-travel, any criminal anywhere could escape the consequences of any crime simply by buying a ticket to another world. Wherever the yacht landed, such a disparity between its documents and its crew would spark an investigation. Moran, at least, would be picked out as a fugitive from Coryus Three. In effect, with six people on board instead of five, the Nadine could not land anywhere for supplies. Blaster in hand, he'd made the Nadine take off from Coryus III with a trip-tape picked at random for guidance. Moran had needed to get off-planet, and fast. But space-travel regulations are especially designed to prevent such escapes. One of the controls on space-traffic required a ship on landing to deposit its fuel-block in the space-port's vaults. The fuel-block was not returned until clearance for departure had been granted.
 They are not murderers.
 They are not murderers.  They do not want to be accused of aiding and abetting.  The crew will alert the authorities when they reach Loris. Moran will be brought to justice for his crime.  They are marooning him as punishment for murder.