WHile I can possibly see some connection between failure to complete basic training and the sort of anti-social and possibly extremist views that may contribute to mass casualty events based on race, the article goes on to state that folks who failed are a threat to the GLBTQetc set. Yet I know of no mass casualty events directed at that group which were not perpetrated by members of that group.
Hate can be general (extremely antisocial) or specific toward a group of people, but it seems the folks who did not complete basic who are so inclined to commit violent acts, including mass casualty acts, had other problems when they got to Basic, and it may be that they were screened out by that, not created by it. (Correlation is not causation).