I'm pretty sure that's a typo. I've never heard anybody from NASA claim they have any way to replace or repair tiles in orbit. Primarily, I would suspect, because the tiles are all unique with individual partnumbers, as they must conform to the skin of the spacecraft, so you couldn't just stock some of them and stick em on with superglue. You'd have to stock all of them, and that would effectively double the weight of the heat shield! Nor is there any NASA equivalent of the 200 MPH NASCAR Duct Tape which can withstand escape velocities of 12,500MPH!
But to your point, I wonder if NASA actually -DID- know how bad it was...if they did, would you advertise this a la Apollo 13? Would you want the crew to stew on it for 16 days? Would NASA management ethically allow a possible shower of debris that could kill hundreds, rather than require re-entry over unpopulated ocean (and hence sacrifice teh crew anyway.) I doubt they knew, but I also doubt they wanted to know.
I suppose that it would be hypothetically possible to stock one of everything in a container and send it up into low earth orbit; then a shuttle in trouble could rendezvous with the container and they could pull out the tiles they need via an EVA. An expensive, convoluted approach, to be sure, but hypothetically possible. I've seen in other posts that claim that even if they had such replacement tiles available, it would be impossible to attach them to the shuttle. I'm not sure if that is because it is truly impossible, or simply that no one has given any thought to developing a method whereby it might be done.
Given that these tiles clearly are and always have been the "weakest link," and given that these shuttles too few and expensive to be expendible (not to mention the lives at stake), in retrospect it is tempting to wish that some more creative thanking had been directed toward dealing with such contingencies.