I'd hesitate to draw conclusions about the American public from this. The decision was made by a handful of executives; and they're probably more worried about post-attack lawsuits than they are about any actual attack.
General nonscientific poll question: has anyone heard a friend or acquaintance say, "I wouldn't go to that movie anyway, I'm afraid of a terrorist attack"?
Most of the reaction I've seen has been frustration and annoyance at the theaters, not fear of terrorism. I think most people are really past that.
õ
Until the next actual attack, anyway!