How is the fear unjustified. Even if it's true that there is no fear of a major outbreak, these people have been in close contact with people who were infected with Ebola. Ebola had over a 50% fatality rate. So to me it's as simple as why risk even one persons life when you can prevent it with a little inconvenience?
If someone is altruistic enough to risk their own life than they should be ok with a 21 day quarantine.