No, that's not an obvious or safe assumption at all, and in fact I believe this is from the study that inspired the article linked in the root comment:

> The lack of objective confirmation of actual amount of alcohol consumed, lack of information concerning alcohol intake before baseline, and inclusion of ex-drinkers with never drinkers in the non-drinker category, as well as lack of assessment of drinking patterns place reservations on the observed findings.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377489/