He's probably been a lush for so long that he's built up a tolerance. Kind of like how Rasputin was able to survive lethal doses of arsenic--he'd been taking gradually increasing doses for years.
According to the DETROIT NEWS he is going through Delirium Tremens while in the hospital so you are probably correct.
When I was a hospital pharmacist we had a fifth of Old Grandad for guys going through DT's. (Spiritus Frumenti)