“He luckily chose guns over bombs. Bombs would have been far worse.”
Actually, he chose both! His apartment was highly boobytrapped. He had set a timer to turn on the stereo blastingly loud at just about the time of his theatre attack. Neighbor complained, and noticed the door was unlocked. He planned to blow the building up! I believe I read the cops said there were enough explosives to also take down neighboring buildings!
He knew enough to set a “timer” for his music, yet counted on a passerby to initiate the bomb(s)?
The timer was likely nothing more than a clock radio with external speakers. He had no sophisticated bomb making skills as alluded to by LEOs at his apartment as evidenced by the fact the apartment is still there.