Sounds to me like the Jihadis succeeded in threatening him and he decided he prefers to live.Could be, but I wonder if this how he has really felt all along and the "Memo" article was written to try and help take some of the heat off of his fellow Muslims after 9-11.
After looking at the article you posted, I searched and found his website, where he lists his articles in chronological order.
It'd be interesting to see what kind of stuff he wrote prior to 9-11.
I also caught a bit of his bio and it seems that he is an Indian Muslim, so that may account for his softer views than most Arab Muslims.
Did you see his article "Memo to Bin Laden"?
http://www.ijtihad.org/BinladenII.htm "Once the war is declared, make no mistake Mr. Saddam Hussain and Mr. Bin Laden, We are with America. We will fight with America and we will fight for America.
I conclude by calling upon you Mr. Bin Laden and your Al Qaeda colleagues and Mr. Saddam Hussain to surrender to International Courts and take responsibility for your actions and protect thousands of other innocent Muslims from becoming the victims of the wars you bring upon them. "
I read somewhere that Khan is a Muslim from India, which would explain that he is not an extremist, like many Arab Muslims. That is why I tend to believe that he really is a more moderate Muslim, rather than someone who was more extreme and just pretending to be moderate.
But his writings lately have become more anti-American. Maybe the anti-Americanism of liberals at the Brookings Institute is rubbing off on him...