@hawkeye10,
There is no reliable basis for the statement--the University has confirmed nothing to that effect.
You're looking for cause and effect to make your own particular case--that because he couldn't cope with school he was forced to drop out and he then saw no future for himself, blah, blah, blah, and that led to his committing these horrendous acts and booby-trapping his apartment.
Except this guy was stockpiling weapons and ammo, and probably the materials to booby-trap the apartment, for at least 3 months
before he dropped out of his Ph.D. program.
What's more likely is that this man began slowly decompensating even before that time, either due to the gradual onset of a major psychiatric disorder, like bi-polar or schizophrenia, which often first appear at around his age, or due to some sort of drug use which affected his mental state, and he began to get more and more caught up in the fantasies of committing the crimes he's now in jail for. And, as he got caught up in the plans, and preparation, and purchasing, and planning explosive devices, he had less and less interest and mental energy for school. And, by the time he withdrew from the program, he knew he'd definitely be committing mass murders and wouldn't be coming back to school because either he'd be dead or in jail.
So I don't believe that anything that happened toward the end of the school semester,like prelims or oral exams, precipitated any of this. And I don't think that people at the University might necessarily notice anything unusual in his behavior--all the the things he was planning and acquiring, and probably obsessing about, were going on in another part of his life, and they were going on in relative secret, they really didn't involve anyone else. His outward behavior might not have altered that much until he got closer to the time he'd put his plan into effect.
Why he hatched on this particular plan of mass shootings, and a major explosion at his apartment, is anyone's guess. It might not be related to rage or anger at all. It might simply be a desire to exercise power, violent destructive power, for it's own sake, just as The Joker might do. Except this guy took it one step further than The Joker, whose exploits were confined to the movie screen, this man actually made it real in the movie theater.
He actually might have been influenced more by the violence of movies, like Batman, and characters like The Joker, than people would like to think, and the influence of either a major psychiatric disorder and/or drugs, helped him to get caught up with an obsession to live out the sort of fantasies of violence he saw on a movie screen.
Other than proving he could do it, and get infamous for doing it, there may have been no other motive, and no specific precipitating event.
