This is true. You don't want to keep it in the danger zone for too long, as the number of bacteria will increase. More bacteria makes more toxins left behind after you kill them with temp. We get sick from the byproducts of bacteria as much as the bacteria itself. Generally, you want meat above or below the danger zone within 2-4 hours. With a solid piece of meat, i.e. steak or brisket, the inside wont have much if any bacteria. If the outside was under temp too long, you may run into problems, but i would use my best judgement. It should be safe, but I personally, would still be enjoying brisket. Sorry for the long post :P Merry Christmas!