As mrs. Guru can tell you, traffic around the convention center, both car and pedestrian, can be crazy. Hundreds of people crossing in front of the building at once can be daunting.
And the train/trolley can be maddening. Once, in 1997 or so, i waited approximately 30-45 minutes outside the con for a train to go by. And thete was a guy who got so frutrated waiting, he was going to try and jump through an empty car to get to the othr side. Fortunately, his more sober friends prevented him from doing anything dangerous.
As the volume of people increases, im surprised things like this or "stab gate" from a few years ago, arent regular occurrences. Tired and frustrated people, many of whom may not have exemplary social skills, can be a recipe for incidents to happen.
I think I'd be really excited about Secret Invasion if it wasn't being written by Bendis. I mean, I like a good Skrull story as much as anyone. But Bendis has proven that he is no good at all driving company-wide events like this.