I cannot see the point why the Taliban will have to legitimize Bitcoin in order to prosper economically. In what way could Bitcoin help the country's economy?
Anyway, before this group occupied Afghanistan recently, they're already very wealthy. In 2018 alone, the group had $1.5 billion in income.
[1] And now that they are the ones controlling the country, there is no reason why they cannot increase their wealth even further. The resources of the entire country is now under their control. They are now in control of the country's taxes as well.
[1]
https://www.bbc.com/news/world-46554097For now, the Taliban are just forming their government. In general, we do not yet know what they are going to do and what policy to pursue. Their first promises are at odds with their deeds. Therefore, for now, you just need to observe what the Taliban will do in power and how to behave.
In Afghanistan, within a month, they predict big problems with an acute shortage of cash and money in general, since almost everything that the central bank of this country had is blocked in foreign accounts. In this case, cryptocurrency could mitigate the situation, however, to what extent they and the residents of Afghanistan are able to accept and use cryptocurrency. However, in any case, the economy needs to be raised with its own national currency.