...p.s. By the way, it would have only taken one gun -- or the crowbar -- or multiple hands.:-)
Perhaps it wasn't "Flight 93-ish" enough to unite the other passengers...who were perhaps more in a "Kitty Genovese-ish" mode/mood.

I have to agree. How can a bus load of people allow someone to get beheaded?
Did they all run off of the bus or something, or did they stay on it while this was happening?
I think it's a duty by just being a human being to take action of some sort.
I think it's pretty presumptuous to pass this kind of judgement on a group of people when this sort of thing happens.
As Anni and Jon both articulated (and maybe Steve too), this was an above the 'norm' incident.
Gross and disgusting and horrifying.
I would love to think that I am so high minded and brave that I would step in front of a bullet (or knife in this case) for a total stranger or even be as good as Tod, Roll On guy and all that on flight 93, and 'do the right thing' but...
to tell the truth I don't know what I would do especially if my child were with me (as seemed to be the case for at least one other rider).
Something really bothers me about how quick we are to pass judgment in cases like this.
I just need to say that.
Another point I'd like to make is this....
As many situations that I have heard of where the 'on lookers' were frozen or scared shitless to act, I've heard of truly heroic just the opposite.
We had a young(ish...30ager) female police officer at a local 24 hour grocery store (my store!) brutally attacked by a nutcase guy who unsheathed a knife from the store and was apparently eating raw meat in the meat department. When she approached him he turned on her and was stabbed many times but survived because on lookers jumped him and a nurse who happened to be there knew how to slow the blood loss, she will survive even though complete recovery may never be possible.
There have been several other similar type heroics just in my town alone as I'm sure there are most places.
(football players passing a burning car pulling a child out comes to mind too)
We don't know all the circumstances but even if we did
how do we know what is the right thing when you're in the middle of something like that.
How completely horrifying it must have been.