"The US in no universe will launch a military action against a rogue, shells-pointed-at-Seoul, nuclear armed nation because they hacked Sony."

Is that your gut feeling? :p I understand it's backed by strong arguments but so were (some) security professionals opinion. They might give updates after the FBI's communiqué and are aware of the limitations of their argumentation. That being said I do share your opinion on the matter...

EDIT: elaborating... EDIT 2: Not sure why I'm getting downvoted. No matter how much I believe US won't go to war there is always a possibility I could be proven wrong. I don't think security professionals analysis was based on "no information at all" (think things we know about North Korea), no more than the analysis we have about US not going to war.