With all due respect to the deceased, the more disturbing thing is a) how did he get onboard in the first place and b) how could it not have been picked up for so long?
It just adds to what I and many others have said for so long- airport security is for show, to make us feel better (and delay us along the way). If someone can place themselves undetected into an aircraft and that same aircraft can fly for x-further days without detection, why not a bomb with a timer...