 Why does Captain Branson warn Ellason that he won't be able to publish his observations?
Basically, it was an instrument which would open distant vistas to colonization, reducing the shoulder-to-shoulder pressure of a crowded solar system. In the tradition of newspaperman and observer, Keith Ellason tried to be as inconspicuous as possible, pressing against a bulkhead, but Captain Branson's eyes sought his several times as Branson listened to final reports from his engineers, record keepers, fuel men, computermen, and all the rest. Ellason was present when a delegation from the Third Quadrant called on Captain Branson, demanding action. Branson remained seated behind his desk, unperturbed, saying, "I have no crewmen to spare for police duty."
 He will be observing an inside job meant to protect the crew
 He knows there are secrets  too gruesome for public consumption  He is going to ask Ellason to sign a Non-Disclosure Agreement  He does not think they will make it back to Earth alive  He will be observing an inside job meant to protect the crew