Quoting the referenced article, in turn quoting a Slate article:

> To sell the stolen industrial alcohol, the liquor syndicates employed chemists to “renature” the products, returning them to a drinkable state. The bootleggers paid their chemists a lot more than the government did, and they excelled at their job. Stolen and redistilled alcohol became the primary source of liquor in the country. So federal officials ordered manufacturers to make their products far more deadly.

They didn't put poison specifically in alcohol for human consumption, but they did put poison into chemicals that they knew would be consumed by humans. At the end of the day, I don't see the difference.