I heard an interview with a person who spends alot of time analyzing the wackos that commit crimes such as this - and it confirmed a theory I've held all along: There are people out there who are just determined to hate and crave being noticed, they look for any "cause" or purpose to use as an idea or excuse to target their hideous actions. They will do violence to get their 15 minutes of fame and their moment on the soapbox to proselytize, and that violence will take whatever form they can arrange - shootings, improvised explosives, fire, poison, etc. At their core, it really boils down to just that, regardless of how they got to be that way - What follows is my own thought on this:
HOW people like this get to be this way can be anyone's guess - maybe mommy didn't breastfeed them or they were bullied as teenagers or whatever - they feel angry, rejected, and are looking to get their chance to get their footnote in recorded history, however they can.
Many/most of these types are delusional and think that they are spiritual leaders of some sort, or philosophers needing to impart their "wisdom" on the illiterate masses. They think that their actions will serve a higher purpose. But they are all just basically angry, ignorant, potentates of their own imaginary empires - and cut from similar cloth, be they Ted Kaczynski, Timothy McVeigh, Derrick Bird, or Jerod Loughner. Rather than providing them with a stage to work from, we should just put them down like the irreparably sick dogs that they are. Give them a fair trial, followed by a first class hanging..
If this person was "sane" enough to plan out this horrible scheme in advance and act upon it, then surely, he is "sane" enough to be held accountable, stand trial, and be suitably punished for it. I am sure that his lawyers will do their best to convince the juries otherwise, but I hope he pays the ultimate price that he exacted from 6 of his victims thus far.