Too many simple, probably wrong answers about Major Hasan

Lisa Miller writes in Newsweek:

Major [Nidal] Hasan may suffer from loneliness, isolation, PTSD, and a terror of being deployed overseas. He may, indeed, be mentally ill. But he was also allegedly exchanging e-mail with Anwar al Awlaki, a Yemeni-American cleric whose rhetoric urges Muslims to see terrorism as a selfless and righteous act for the greater good of the global Muslim community. In his tract "44 Ways to Support Jihad [.pdf]," al Awlaki writes, "Jihad today is obligatory on every capable Muslim. So as a Muslim who wants to please Allah it is your duty to find ways to practice it and support it." Even if Hasan was not, strictly speaking, an enlisted man in a terrorist cell, he was exposed to these ideas. They may have framed his thinking. They may have given him a "rationale" to act as he did. Either-or choices don't satisfy. Bruce Hoffman, professor at Georgetown's School of Foreign Service, puts it this way: "Just because somebody may be mentally unstable doesn't mean this isn't an act of terrorism."