I don't think so. Not in the current culture surrounding the public's understanding of depression and mental illness. Just about everything that I have read in the media coverage following this unfathomable tragedy serves to characterize the perpetrator as a sick and twisted deviant, someone so evil that no one could ever really relate to him. Well, if that's the case, then this tragedy was likely not preventable. I, even as a forensic psychiatrist taking in all that I've read about him, can hardly say that I know this man. However, the things that have been described as leading up to his act of aggression are the kinds of things most of us can relate to, a failing relationship and problems in his career.
So we can't know whether this particular event could have been prevented, but if we want to prevent any similar tragedies that might be prevented in the future, we need to find the things about this man that we can all relate to because that will be the only way we can talk about reasonable ways to identify and help at risk individuals.
I am in no way saying that any of us could have perpetrated what this man did. Almost certainly, very few people could. But what I am saying is that if we want to thwart these individuals we need to spend less effort identifying how they are unlike us and more effort to identify how their stress is like anyone's stress and figure out how to get help to anyone going through a difficult time.
Sure, it makes us feel better to know that we are nothing like this man, but if we really want to be safer, we need to figure out how to make it easy for anyone to get help when they need it.