Because a flight ban recognizes the legitimacy of international borders, OUR borders in particular, and both parties believe in and promote globalization and a borderless world.
One of Obama's top health advisers (Ezekiel Emanuel) wrote this October 1, 2014 in JAMA:
"there are obligations of global justice to combat Ebola and strengthen health systems and infrastructure in affected countries in the longer term. Advocates of so-called cosmopolitanism—a key position in the philosophical debate about global justice—argue that national borders have no moral significance and that all people, regardless of where they live, are entitled to the same education, health care services, and other social resources."
THAT'S what they believe. That's what a flight ban rejects. And that's why they won't do it.
So putting millions more people at risk of contracting and spreading a deadly disease by refusing to contain it, is moral?
These people are utterly INSANE. They have no common sense. They don't even have the sense to survive. They should not be in charge of ANYTHING.
Maybe the good doctor should be in Liberia, ministering to the sick and dying.