By the Obama administration's definition, JFK's assassination was simply "workplace violence".
If they awarded the people who were killed or wounded a purple heart, they would be admitting it was an act of terrorism.
This is an easy case. Hasan was in a U. S. Army uniform which means if he was acting for a "foreign power" he was a spy and could be shot. Another reason why they won't award the purple heart or allow him to say he was acting for the al-Queda.
Calling this anything but workplace violence would mean they would have to admit that the jihad is still going on and that al-Queda is NOT on the run.