In order to keep everyone safe it makes sense to shut down the government buildings and get everyone home safely or prevent nonessential personnel from coming into the office in the first place. This helps to minimize the amount of commuters on the road when the blizzard hits. Last year we witnessed the catastrophe that happened in Georgia, where there were backups all over the city as people tried to rush home at the same time during the height of the storm. Being proactive and getting ahead of the storm is the way to go.
While they might want to maintain some emergency workers on call in case of fire, a break in, or a sudden need for emergency shelter, having workers come in during record snows is a risk to the employees and is not worth taking a chance for. There is nothing that can't wait until tomorrow.
I think it is logical that government should plan in advance the event of extreme storms or floods that will prevent people from working or even coming up to work. The population should stay at home and limit their transportation as much as possible so they don't become a danger to other people on the road.
The government should keep some of their critical buildings open during the snow storm. Although the non-critical buildings can be shut so that the workers can shelter safely in their homes, buildings that house the emergency operations centre, the paramedics, the fire department, etc., should remain open in case the need arises to use their services.