I see a lot of back and forth over whether Sodini was only mentally ill or a misogynist or ???
It's obvious that he was mentally ill and may have had other conditions that exacerbated his social ineptness. But the attitudes about women, men, race, religion, and what he would need in order to gain status with other men (a young, pretty woman by his side) came from society. Mental illness was the fuel and our culture was the vehicle leading him to his final, explosive crash.
A good therapist able to both treat the mental illness and challenge the distorted thinking (which is a hallmark of depression and other mental illnesses) while countering the cultural message could have turned it all around.
But men who admit they need therapy run counter to our serious stigma against mental illness and against men admitting they are "weak" in some way. It doesn't seem to have crossed his mind even as he talks about being a malfunction. The closest he gets is thinking he might need a personal coach. But he feels so much shame at his lack that he doesn't want to tell anyone about it.
When I was training to volunteer on a suicide crisis line (another thing that might have helped him), we were taught that the more isolated people are, the higher their lethality. While I'm not saying that women should have taken it upon themselves to let him extensively proposition them, it is clear that neighbors and others could and did sometimes have a positive impact. Neighbors noticed his deterioration as well. It can be helpful to ask, "Are you OK? Do you need to talk?" And when you discover how troubled someone is, "Are you having thoughts about suicide?" If yes--"Let's call the hot-line together."
Or, if you are fearful of getting that involved, at least put the number of the suicide hot-line in their mailbox with a nice card, anonymously. At least he (or she) will know you cared enough to do so. That can mean a lot. You can see the ambivalence about what he was planning in his diary--this kind of back and forth is typical of a suicidal person as well. Positive interactions, even a friendly "Hi" in passing, can help tip things back to the positive.
TTY: 1-800-799-4TTY (4889)
You can also give a gift of the paperback: Feeling Good: The New Mood Therapy by Dr. David Burns. Maybe a therapy-phobic person will at least pick up the book and learn something from it.
Here is the html version of his journal: http://georgesodini.com/20090804.htm