I'm wondering if DHS has gotten wind of something that's scared the snot out of them.
I doubt it.
Of course it's a security concern. Super Bowl is one huge target. Literally thousands could be wiped out while billions watched on tv around the globe.
I flew into New Orleans on Super Bowl Sunday 2002, the first following 9-11, with an arrival about an hour or two before game time. You can bet I checked out every passenger on that flight. Fortunately, the crowd was mostly those wild and crazy Cajuns returning from a DC Mardi Gras ball.
If the tailgaiting ban was considered long ago, however, the NFL should have considered renting an equally huge parking area nearby and letting people do their tailgaing thing there, then bus them over to the stadium. Some alternative should have been planned and probably will be in the future.