I would if I were in your shoes.
You're not buying him booze, you're making it possible for him to have a safe enviroment in which he can recover.
I'm guessing he has a history of relapse because of your lack of hope. Which is why you're questioning this gesture...Maybe others will think differently but I don't give up hope on someone especially when they are asking for help and have no other means. He's already been on the streets. I don't see him having another option.
Is it Codependency or Compassion?