Mtb is an intracellular pathogen. It invades our cells, the very same cells that are supposed to kill bacteria (the macrophages). This is why treatment of TB takes six months. Vitamin C, at a dosage lethal for Mtb as described in the article, cannot be used to kill the bacteria in our cells. The importance of the article is that it identifies a potentially intereseting difference between Mtb and other bacteria.
As for vitamin C, this is not some kind of a miraculous drug; it is just a co-enzyme required for a few particular reactions in our metabolic pathways. We, humans, are mutants, we lack the ability to synthetise vitamin C -- along with our cousins, the monkeys, although most animals do synthetise it on their own. Lack of vitamin C impedes the metabolism. However, only little of the co-enzyme is needed, and once vitamin C is no longer a limiting factor, it has barely an effect.
Think about that in terms of a network. If your wireless router is extremely slow, buying a new one will increase the speed of your connection. But what good is a super fast wifi router, if the outgoing connection runs at 10Mbit?
Vitamin C is also an antioxidant, and this is why some people (quite incorrectly) think that taking large doses of vitamin C are beneficial. However, there are two forms of this compound, L-ascorbate (vitamin C) and D-ascorbate; both are antioxidative, but only one is a co-enzyme. D-ascorbate, however, shows no beneficial effects.
Big pharma has not much interest in preventing the use of vitamin C in Mtb treatment. Mtb drugs are cheap, generic, and effective; the main reason why Mtb is a problem for much of the world is lack of fast and cheap diagnostic tools. You see, 2 billions (2e9, one third of worlds population) are infected with Mtb, and of these, only 10% will develop tuberculosis during their lifetime. However, we don't know which, why, and when. Also, when a person falls ill, it is not a quick process like a flu; rather than that, a person starts feeling unwell, caughing and becomes infectious over weeks before she finally decides to see a doctor. Here is a review article I wrote on TB and biomarkers: http://www.ncbi.nlm.nih.gov/pubmed/23181737 (full text behind a paywall, unfortunately).
Pauling believed that taking large doses of vitamines will prevent cancer and took large amounts of vitamin C throughout his life. In 1994, he died of prostate cancer.