Not all immigrants have a green card. Green card means permanent residence; 
Also, the MAVNI pilot program was opened to those with international student visa too, which is a non-immigrant visa that lets foreign students stay here legally (with limited work authorization). Technically, those students are "non-immigrants" but the news article puts everyone under term "immigrant" because these soldiers have obligations to fulfill under their military contracts currently-- which makes them a sort of an immigrant. 

No fraud here.