I would want to kidnap it! lol But thats stealing... Anyway, I think you should politely and as nonchalantly as possible ask the room-mate why his enclosure looks as it does. Something like, "Hey, I own a bp, where did you get him?" Then you know, slowly get into a convo about everything and ask " so what do you like to keep his temps at?" Which will be responded with "I don't measure them" and you can try and get into a little more.

If he completely does not care to talk about it, well that is animal neglect really. Not to be mean but here in Ontario, you could call Animal Control for neglect and have the snake taken away, then adopt it! But yea that is a sticky situation, I would like to hear what others have to say as well.