why does jim agree to bring a glass of rum to bill, knowing that the doctor believes rum will kill the captain? chapter 3

The captain was making a racket, and Jim's father required peace and quiet.

He was growing more and more excited, and this alarmed me for my father, who was very low that day and needed quiet; besides, I was reassured by the doctor's words, now quoted to me, and rather offended by the offer of a bribe.