There are other factors than just "time" at play, though, that you have to take into consideration.
You may have the time to reasonably secure the Sugar Bowl from known and predictable issues, but not from the unknown potential threat that this attack raises.
Additionally, securing a major bowl game takes a lot of law enforcement resources that are also probably in high demand following a significant terrorist attack. Even if you can reasonably secure the Sugar Bowl, is it worth the LEO resources cost when you also have a time-sensitive investigative & potential prevention task underway?
Finally, even if you're fairly confident that you can secure the Sugar Bowl and have the LEO resources to allocate, there is still value to taking a small amount of additional time to be very confident given the change created by this terrorist attack. That's not simply CYA'ing, that's taking steps to assure reasonable additional precautions against a late-breaking and potentially significant threat.