The six foot rule

The film's title refers to the "six foot rule", a guideline from the Cystic Fibrosis Foundation which states that cystic fibrosis patients should be kept at least six feet (2 m) apart to lower the risk of cross-infection.[11]I

As mentioned a sneeze can travel up to five feet. So, adding another foot is for saftey. It is a huge risk to go closer, that is why it is such a big deal!