I don't know you, your roommate, nor your relationship. I would ask myself these questions:

How much time do you want to invest in teaching him?
How will you feel if he goes broke?
How would you feel if he became better than you?
How well will you know him in the future, and how do you think it will affect your decision?
How do you or would you feel having him in your games as a fish or good player?
How does your upbringing, religion affect your decision?