Nice evasion, I take from your comments that everyone should be able to arm without regulation. B/c you can't regulate against insanity, then you must let the sane choose whether they arm or not.
I do feel bad, this bad person had bigger plans with bringing down a building with innocent people as well to distract authorities as he got away. The violence displayed in this act should dealt with the most harsh penalties and I believe there should be more than just the shooter punished. Someone else knew he was at the very least capable of this, if not then what the eff is the agency known as Homeland Security cashing checks for?