The whisky business is Andy's hobby. Note that what gets sold is the stuff that doesn't meet Andy's very high standards (80% of people would consider the leftover as very good themselves; there are collectors in Earth who'd pay significant amounts for certain batches). He also does small amounts of Firewhisky, which the Wizards want a lot of. Occasionally he does Vodka as well.
In this case he doesn't get enough demand to put together a full time business, but what he does get is more a specialist market.
In this case he doesn't get enough demand to put together a full time business, but what he does get is more a specialist market.