Asking boyfriend's son to possibly help with the baby

My boyfriend said that's a bad idea and depending on when I do it I'll just wind up getting yelled at. His 19 year old lives here and pays $150 in rent. He works from 10pm to 8am. And goes to school 2-6 everyday. Now my boyfriend knows better than to wake his son because his son will bite his head off because he's exhausted. So if he asks for rent it's always when he's about to leave for work so he's not as cranky. I'm just so tired when my boyfriend is at work and could use a nap.... But his son sleeps about 5 hours a day so it's probably not a good idea....

@Kathis my boyfriend does help me... He just has a lot between work and therapy. He sees his therapist twice a week now because for a while he's been having accidents at night. He's trying to figure out why they started again. When he's home he does help. I get what you're saying though.

@Kat my boyfriend is putting the money away in a savings account. He's gonna give it to him when he moves out.