Isn’t the net effect of the first also zero? (No net carbon was added to the atmosphere than was there on Dec 31, 2020.)
There are net emissions from all the equipment and processing involved. But of course, if buying carbon offsets is a valid way to offset burning coal, it is also a valid way to offset all the truck, tractors, etc associated with liquor production. So you are correct.
Close to zero as growing the grain was not "free" conversion from atmospheric CO2 to glucose or w/e.