This sounds like a "work accident." It is entirely possible that he was trying to plant a bomb somewere -- the botany/microbiology building was nearby and would be a logical target for an ELF eco-terrorist.
The fact that he had significant stockpiles of explosives in his apartment make it look less likely that he intended to be a suicide bomber.
He might have thought that security would be diverted to the football game, so he could slip into any building on campus without discovery.