Funny enough, in his manifesto this guy is saying the same thing. He's for banning the types of weapons he will be using.
The copies of his manifesto is corrupted info, I've seen about 4 different versions claiming "uncut" "original" ect. I can't say for sure, but it seems the language pattern changes in his "anti-gun" segments, so my guess is that is added on to further an agenda. Look around for yourself, I'm not saying anymore in fear of being politically incorrect.
I will say I feel for those affected including the victims so far, and those that are terrified in and around L.A. right now. If I lived there and resembled his appearance in any way, I'd be scared as hell.