 Why didn't Moran kill Harper?
I. Moran cut apart the yard-long monstrosity with a slash of flame. Moran, naturally, did not mean to help in the carrying out of the plans which would mean his destruction one way or another. From the viewpoint of the Nadine's ship's company, it was simply necessary to get rid of Moran. Moran disagreed, but he did not answer. 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. And Moran was the extra man whose presence would rouse space-port officials' suspicion of the rest. Only people accustomed to desperate actions would have remained so calm when Moran had used desperate measures against them.
 Moran is not a murderer at heart. He only killed the other man to save a life.
 Moran is not a murderer at heart. He only killed the other man to save a life.  Moran would rather kill Burleigh. He is waiting for the right moment.  Moran is not a killer.  Moran likes Harper. Harper is a decent guy.