Here’s what the PLA could hope to accomplish with such an attack, if it was a probe for a later attack on a larger scale (such as the beginning of a war).
* To instigate more “gun control” laws in the USA.
* To harass, of course.
* To probe for the possibility that they might take out most of a cycle of officer candidates in our nation.
Be interesting to see the head bashing ol’ Cool Hand Lu would have received at Quantico.
Worse case would be that this shooter was one of a group of sleeper agents who were in the process of planning coordinated attacks across the country. After catching his girlfriend in bed with someone else or some other problem that led to the early shooting, he then executed his specific plan early. Just throwing out possibilities.