Retired USAF air traffic controller here. Not sure why the arriving aircraft aborted his landing. The separation between these two aircraft is that the departing aircraft must be 6000 feet down the runway and airborne before the arriving aircraft crosses the runway threshold (FAAH 7110.65, paragraph 3-10-3, a, 2(c). The article is not very clear but just because the departure was cleared for takeoff when the arrival was 1 mile from the runway does not violate separation standards.
+1