As has been said in this thread, they were defending a static location.
By most definitions short of Mad Max, SHTF has happened many times in modern history. Venezuela, Bosnia, Katrina, the LA Riots, Turkey, Egypt, and countless localized events tied to natural disaster provide many examples. They show us that concealed handguns will remain the best "on the go" option unless it becomes clear that there will be no consequences for carrying a long gun. That would require a sense that a power or service vacuum was at least long term, if not permanent. Power and service vacuums tend to be very short lived.