That strain WAS airborne. However humans did not seem to contract that version.
With the virus reproducing by the billions in a host, the chance for a seven protein DNA to mutate is huge. One will mutate to become airborne, while not hostile to humans. The next mutation may be airborne and fatal.
This potential mutation becomes more likely with every single case.
With viruses like Ebola the danger is in the speed and complete takeover of the hosts.
Technically, some of the humans did test positive for the reston virus, but they were asymptomatic. Hence there was no progression through the various stages of the disease you would expect.