"Dates and Seeger, like others in the theater, thought the man and the smoke were all part of the show."
Well that's an interesting idea...
There are all sorts of wicked, twisted people in the world. I should know. Misguided, lost, dreaming of cruelty. Alone on the internet, getting all sorts of weird ideas. Individuals who think of death, suicide and genocide way too much. Way too self-absorbed, with no-one else near them to think about, their lives an isolated, gaping void of meaninglessness.
"What the hell", he might have thought, "let's pull the trigger because that will get me known. I refuse to be your average Joe." So dumb. So immature. So deliciously, ironically serious.
Seriously, he probably needed friendship and sex, and everything would have ended alright. Of course he would still exhibit his sociopathic/psychopathic tendencies, but those would get ironed out a little bit over time to make him a stable, reasonable human being.