First off, there was no sniper rifle at the game, that was pre-game only for a demonstration for a weapons company. Only binoculars were used during the game.
http://deadspin.com/super-bowl-sniper/
Secondly, the Super Bowl has a ton of important people there... you don't think there's armed security there to take down a threat if necessary?
My guess is they never would - that many moving people packed in so tightly if they mistake something for a threat or shoot to protect a celebrity and miss- I can't see them ever doing it or if they did persmiisipn ever being given to actually shoot
