Hoseason is an interesting contradiction in terms (sound familiar yet?). He's a "great churchgoer while on shore" (9.22), and the name of his ship is associated with religion. (The Covenanters were a seventeenth century group of Scottish Protestants who wanted to set up a system of church government based on Parliamentary representation rather than a king. Check out either this site or our note in the "Detailed Summary" of Chapter 5 for more on the Covenanters.)
But Hoseason is an absolute hypocrite. He's sorry when his first mate, Mr. Shuan, kills Ransome the cabin boy, but why didn't he step in to stop Mr. Shuan's systematic abuse in the first place? He imagines himself as a man of God, but he's willing to murder Alan Breck for his money belt. And he would have let Davie die in the hold of his ship were it not for the intervention of his second mate, Mr. Riach.
Davie's ability as a narrator really shines through in his handling of Hoseason. Remember, Hoseason is planning to sell Davie to a plantation in the Carolinas for profit. As imperfect as Davie is, he's still able to sympathize with his enemies. This gets us back to our larger point about Stevenson's interest in complicated, contradictory characters (like Davie and Alan).
Yes, Hoseason is a complete jerk to Davie, but Davie finds it in himself to describe Hoseason's feelings about his ship relatively sympathetically:
His brig was like wife and child to him; he had looked on, day by day, at the mishandling of poor Ransome; but when it came to the brig, he seemed to suffer along with her. (13.36)
Obviously, this assessment is not completely nonjudgmental: Davie notes that Hoseason gave Shuan's abuse of Ransome a pass. At the same time, Davie does portray Hoseason's genuine pain at the loss of his ship. He allows Hoseason some roundness of character, portraying him less like a stereotypical villain and more like a human being.