Jihadist reads the manual, decides to target unarmed military personnel in-garrison. Luckily the plot was foiled.
By the way, it should be pointed out that the soldier probably isn't allowed to buy privately owned weapons without registering them on base and getting permission from his commander. As a junior enlisted person, he probably is supposed to live in the dorms and thus must abide by the base's privately owned weapons policy. It is almost as if people who go AWOL, assemble bomb making materials, and plot treason in time of war don't care about gun control laws and regulations.
It could be that all the publicity around the Ft Hood shootings followed up by lots of terrorist propaganda highlighting has made it clear that most military members tend to be disarmed by policy at home station. Then again, this is a totally logical policy for most military leaders to implement. After all, if they allow weapons on base, and someone does something stupid or unsafe, their career is toast due to their perceived bad judgement. If the instead prohibit weapons and create a victim disarmament zone and then a terrorist attack kills a bunch of their people, it is a tragedy or maybe an intel failure, and then we get all concerned about our diversity and sensitivity training.