Here I think your wrong . . .
According to what was posted by PhiKapMom earlier - the parking facility doubles as a "food hall" etc... during half time - I do know that the ticket office is located there . . . According to what we've heard *if* the bomber was intending to detonate during half time - this would have been a great target! (crowded, inclosed, possibly material failure and collapse of structure.....)
I was speaking more to your building 91 comment...
Under the parking garage are all kinds of food stands and places selling OU merchandise. It is crowded at halftime even on the eastside where we sit. People also leave the stadium at halftime to go get some beer and get passes to get back in the stadium. You can hardly move around down there and lines are long.