What are the odds? The real explanation is that leftist activists hung out with Al-Queda types and talked about how bad the US and Israel are. Not that his father knew Mousaui was a terrorist, just they travelled in the same circles. I bet this pattern is probably repeated in other cities where recent ME immigrants and old line lefists (communists) are present.
That's what I'm trying to figure, the odds. The pieces are dribbling out becoming more fantastic as we go.
Some possibilities (just throwing ideas out):
He went and offered himself to be used as a bargaining chip for the release of Al-Queda agents under our control.
He was working for the CIA and was found out. People who knew him have said he was a great guy who didn't believe in his father's politics.
He was friends with Al-Queda operatives, like Dialup Llama states, and was attempting to help them in some way when it blew up in his face.
I'm convinced something else is going on here. We've only heard part of the story. The guy's dad is clearly a leftist wacko, and I wouldn't be surprised to find out the son was actually working in some way with the islamo-fascists. Nevertheless, the beheading proves just how barbaric these guys are.