Why the Seyyeds in Iran want to be in NPT?

One of the questions one asks regarding this whole nuclear fiasco, is why don't the Seyyed Zeolots of Iran not get out of the Non Proliferation Treaty (NPT) altogether? As the article below points out, the treaty is not worth the paper it is written on, because the disarmament on the original five members is just not happening. Fair enough, but that still does not explain why the Seyyeds do not become another Israel, India, Pakistan, or North Korea? Could it be that the Seyyeds and folks like ElBaradei actually want to use the NPT as leverage against members such as United States, when considering the current geopolitical environment in West Asia?

http://www.washingtonpost.com/wp-dyn/content/article/2007/04/29/AR2007042900487.html