Is it possible gym and health junkies spend time and money on smoothies, food fad, new exercises rather then stay at home or in the pub drinking alcohol in the first place. So the numbers are already stacked.
Alcoholics I have come across are seldom preoccupied with a hobby, interest or even people. They try their best to hold on their jobs rather than an interest in the job. Alcoholics are trying to keep it together and the focus is not exercise but to see how they can get out of their dependencey by attending AA, seeking counselling etc.
Never heard an alcoholic say that he heading to the Gym to stop his dependency.
I really can't see the correlation and sampling might be faulty. Its like sampling the fitness levels of firemen and policemen. Doesn't take rocket science to figure which would be the fitter cohort by a mile.