The day after a hurricane is a Glorious Day of Eating. With the power off, the stuff in the freezer must eaten when it thaws. Most expensive stuff first, so grilled steak and smoked brisket, both cooked without power.
Not sure why you would overstock on brisket though..
My guess is the supermarket wants to get rid of the expensive stuff it will lose without power, so they put it on the news and make it seem scarce. My guess is a lot of people who didn't even think of brisket ended up buying two. But I don't know much about Texas maybe no one doesn't think of brisket.