With that in mind, it's worth reconsidering this:
It does seem clear that the military ignored some pretty obvious warning signs. But just like there's significant difference between being an intelligence officer with the last name Silverman, and being an intelligence officer who repeatedly lies to his superiors, there's significant difference between merely being a Muslim in the Army and being a soldier attempting to cooperate with Al Qaeda.
It actually doesn't seem clear to me that there were many warning signs that this guy was going to turn homicidal. He probably shouldn't have been in the Army. But that's different than saying it was obvious that Hasan was about to go postal.