Fascinating to see that they started with the most interesting virus rather than the most commercially valuable virus. Stopping the common cold is probably worth 100 times more money, but stopping Ebola is more scientifically interesting. Kudos.
That and Ebola is cool.
Just putting together a clinical trial would be incredibly expensive because of the difficulties in picking out patients who have the virus your drug treats while they're still early enough on in their illness to be treatable. I may be wrong, but I thought that there actually were some early phase trials of a drug to treat rhinovirus, but they were stopped because of logistical difficult and expense.
Ebola was probably chosen because it is a rather stable virus and has only relatively few serotypes.
But as to why this group of scientists chose Ebola: they have been working on Ebola for over 20 years, so they made that choice long ago. Every human virus has a scientific community of experts who study it.
I just checked the wikipedia article, and the Ebola virus is not naturally transmitted as an aerosol (http://en.wikipedia.org/wiki/Ebola#Transmission). It is transmitted through bodily fluids, including supertiny droblets but that won't effect more than the ten people closest to the infected person on that plane, and before they have a chance to infect anybody else the worlds medical system will have indentified and dealt with the case.
In addition, the virus kills within 2-21 days, so it is unlikely to have time to spread to that many people from each source.
Therefore, this won't be the new black death, but that won't stop the media from comming all over the story.
Ebola is a frighteningly deadly virus, so this sort of research is very encouraging, but its lack of an aerosol delivery mechanism and its quick mortality cycle both mean that it will likely never cause an epidemic on the scale of Bubonic Plague.