I'd blame it on a sick twisted freak.
Since it would be very hard to ban someone who is dead, I'm pretty sure that wouldn't fit with the liberal agenda. It is much more entertaining for them to blame it all on inanimate objects which had little to do with the number of deaths. Rather than blaming the most obvious accessory (the BMW), they aim at the gun which they hate anyway.
Let's be perfectly honest, the one thing that the liberals least want to address is how many of the most recent mass murder perps had been under active psychological counseling. I'm pretty sure that the answer is all 12 of the last 12 mass attacks. Any question of the liberal lovechild of therapy is of course forbidden....