They are able to stop not because they are worried about another 9/11, but if something happens, the class-action suits will fly all over, that scares the theaters. So, in essence its not the North Korean dictator or his minions, but the good old lawyers of US&A.
What you are doing is "victim blaming". It's not Sony's fault. It's not the theaters' faults. It's not the lawyers's faults.
It is the fault of the people threatening violence against moviegoers.
edit: I'm not commenting on the overly litigious culture of the US or easily panicked mentality over any threat. Those are fair critiques of the US. However, both of those would be moot if it were not for a credible threat of violence from some person/group. This philosophy of culpability pre-dates the US legal system.
No, the fault really does lie with the overly-litigious culture of the US.
Did you know that if you graduate from med school in Canada, they advise you not to step forward if you're on a US flight and someone asks if there's a doctor on the plane?
I'd be interested to see such a citation as well. Quick searching shows that the US (and other countries such as Canada and the UK) have Good Samaritan laws that protect doctors assisting people in such situations. Specifically:
"The Aviation Medical Assistance Act of 1998 ensures that if you're flying in the United States, even if the airline is not owned by a U.S. company, you have Good Samaritan protection."[1]
I also found one article interviewing a doctor who answered the call who mentioned that no physician has been successfully sued for assisting in an inflight medical emergency.[2] A claim that he actually backs up with a citation.[3]
A certain amount of victim-blaming is appropriate, IMHO. You can't make the world a perfect place, and if you tried, you'd likely make it much worse (Orwellian).
The US needs a more sane legal system and the world needs an appreciation of higher quality software systems, made more slowly and carefully.
EDIT: "made more slowly and carefully" is more specific and simplified than I needed there, feel free to ignore it...
I don't even think it was that. I think enough theater chains opted out, Sony assumed more would follow, and they realized a limited release didn't make financial sense. Sony knows the threat against theaters was bullshit. The theaters didn't have much to lose, there's other movies they can put on that screen, and this didn't even look like a good movie anyway. Maybe they just saw an opportunity to put The Hobbit on another screen and used this as an excuse.
It's also in no small part due to the already controversial nature of the film. I'm pretty sure that a vague threat emailed to reporters wouldn't cause Fox to cancel Avatar 2.