Not a good idea though. If people see the Taliban use it (and let's face it, that's inevitable if the common people start using it) it will give bitcoin a bad name that we can't really recover from as long as it's used there.
I think I remember reading a couple of years ago that terrorists were found to be using Bitcoin to buy weapons. I cannot remember if this was a legit claim but I have heard other people say that they think Bitcoin is used by criminals it does not matter if the claim was legit people will believe it without researching it.
Bitcoin is not yet fully payment system like fiat. Bitcoin is high volatile and common people of Afghanistan would not like it. Well devolped countries should choose bitcoin for payments purpose than off course some small countries will also adopt it.
Bitcoin is a full payment system and operates like fiat but with improvements the problem with Bitcoin now is the fees and the high volatility that has nothing to do with Bitcoin not being a full payment system but the nature of the people using Bitcoin. Afghanistan is not a small country and is one of the richest if you count the amount of oil they have.