I think the likelihood that a young man who had a slight connection to the 20th 9/11 hijacker and was then butchered by Al Qaeda is slim. Not impossible, but slim.
Given his father's remarks, I'd say there is more to this story than we are being told.
I'd say his father's remarks were typical of someone who cannot openly condemn the enemy but yet try to get the enemy to "understand" his departed son.
Sometimes a coincidence is a coincidence. Besides, a slight connection is not a big deal. Many people had slight connections to historical events.
IF david Horowitz is murdered by black radicals, does his previous EXTENSIVE connection to the Black Panthers mean a thing?