It's very possible you could buy a brisket tomorrow and it will be safe, and here's how: If you have a curing or beer fridge that you keep a little colder than your kitchen fridge, say 35° you can wet age a brisket in the cryo packaging, I do this for 20 to 30 days routinely, provided I know the "kill date" which is found on the end of the cases in the store's walk-in cooler. Here is how this works safely.... When fresh meat arrives at a store it's shipped super cold, then held in a walk-in cooler that is below 32° or 33°. It can be stored at these low temps for a long time. When a store moves meats from the boxes to the counter, they weigh it, print a label and determine a "sell by" or "use by" date based on the kill date and the temperature in the meat counter. Stores assume your kitchen fridge is 38° to 40° and so for safety they might calculate the sell by date for 4 or 5 days. But since meat might have been in the walk in for weeks, the sell by date is not accurate to use for wet aging.
So, ask the meat cutter what briskets they are holding in the back. Tell him you want to wet age a packer in the cryo, and ask him to look at the boxes for the kill dates that are at least 2 weeks ago, then bring out 3 or 4 for you to select from. Pick a nice one and they will go back and print a label for it. The label will show a sell by date, but you can ignore that since you will be holding and aging it for 15 days in your cold beer fridge (If the kill date was only 5 days ago, you have 20 or 25 days to wet age. I write the kill date right on the label so there is no confusion.
Any cryo packaged meat will contain some purge, which is a red liquid some folks think is blood. Upon opening the package you sometimes notice a slight odor (nothing like spoiled meat) and the odor will dissipate in about 10 minutes. I usually put briskets into a bus tub, and give it a spray with cold water, and wipe dry with paper towels which really kills any odors, then move to a cutting board for trimming.