What conclusion does Marlow draw?

At first Marlow thinks the pilgrims and himself just don't look appetizing. Their pink flesh and sickly demeanour might be unappetizing. Later Marlow develops another theory,

"Restraint! What possible restraint? Was it superstition, disgust, patience, fear -or some kind of primitive honor? No fear can stand up to hunger, no patience can wear it out, disgust simply does not exist where hunger is; and as to superstition, beliefs, and what you may call principles, they are less than chaff in a breeze. Don't you know the devilry of lingering starvation, its exasperating torment, its black thoughts, its somber and brooding ferocity? Well, I do. It takes a man all his inborn strength to fight hunger properly. It's really easier to face bereavement, dishonor, and the perdition of one's soul -than this kind of prolonged hunger. Sad, but true. And these chaps, too, had no earthly reason for any kind of scruple. Restraint! I would just as soon have expected restraint from a hyena prowling amongst the corpses of a battlefield. "