People off most cultures drink, not just westerners. See Japan.
Also people have drank for thousands of years and I’ve not seen any studies showing there’s more drinking now not that that hypothetical increased drinking has increased cancer rate.
Yes it’s obviously bad and causes cancer.
If this is in the US employment contracts are virtually nonexistent.
If a policy doesn’t discriminate against a protected class, it’s pretty much legal. Your recourse is to find another job.