As long as governments benefit more from modern slavery (which is what fiat money truly is), than from a form of money than is immune to outside control, they will not adopt BTC.
Russia or even places like Iran or Venezuela may have their problems with outside powers, but even for those countries fiat is still essential in extracting labor from their citizens.
On top of that Uncle Sam would probably "find" some weapons of mass destruction real quick if a country adopts BTC as a currency. Heck, look at Iraq, when they tried to adopt another fiat than USD (EUR).

so much relevant truth in one post
EDIT: however consider that in the end, the government really has no say in what is used as money by the population. If they extract labour from the population under decreasing living conditions for too long, they might wake up, come to their senses and exert the power they have. A dangerous game they play. Also a dangerous game the US specifically plays, by the way, misusing their
exorbitant privilege like that (for those who don't know the
Charles de Gaulle speech from '65, it's a must watch)