Apparently the Taliban plan to use the contracts as part of a propaganda campaign to disgrace the tribal elders who, having signed the contracts at gunpoint, now have the temerity to not adhere to the terms. Written contracts are not unknown among the tribes, especially when some particularly complicated deals have been worked out. But it's also understood that contracts signed under duress, even if oaths were sworn to Allah along the way, are not binding.
While all of this may make for some interesting propaganda (for both sides), it would likely make an even better political satire, either as a novel or a movie treatment. Another case of truth being stranger than fiction.
In Afghanistan, the Taliban are unhappy that some tribes are quite willing to shift allegiance to whomever is stronger in their neighborhood at the moment, even if its the government. Especially if it's the government. To try and address this problem, the Taliban has taken to forcing tribal leaders to sign contracts. These documents include condemnations of the Government of Afghanistan, and commit the leaders and their tribes to support the Taliban and its brand of Islam. Precisely how these "contracts" are supposed to prevent the tribes from shifting allegiance back to the government when the military control of their region changes, is not clear.