Bad idea. VERY bad idea. If the relationship is in trouble now, it will only get worse if you live together. Plus, then you will be stuck and getting away (not that if appears you ever intend to actually do that) will be much more complicated. He can't run from his drinking problem. It will follow him wherever he goes, and if that means he is living with you, it will be the huge elephant in the room with both of you. His mates don't hold him down and pour the alcohol down his throat. He makes a conscious decision to drink.
As always, you are going to do whatever you are going to do, but moving him in with you won't give you any more control. In fact, it will give you LESS control. It will only bring his problems right into your face 24/7.