Alcohol is used as a preservative, this being a distillate it should not be surprising that it is still 'fit for consumption'. Given that people will drink window cleaner and glycol it should be even less of a surprise but I figure the article meant that his was originally intended for consumption rather than as a cleaning product.

Poland has a fairly active bootlegging industry, and a typical reward for some favour or other is a small bottle of the local poison. Those bottles can be quite old as well and I've yet to hear of someone complaining their vodka had gone bad.