A lot of food grade drums have a light tan colored liner or spray coating inside to create a barrier between food contents and the steel walls. I'd think that's what they're describing and if so, I understand those do come out pretty easily with a good burnout or even Kleen Strip (search the UDS thread). The red liner is the one that is more resistant to being stripped out. (Sandblasting seems to be the easiest and most satisfying solution, if you don't mind the few extra bucks). So short answer, you're probably in good shape.
I plan to go with the Big Poppa kit as well. They ran out just as I was going to put in my order at long last!