Why not? Bitcoin doesn't need to be legal tender if the government want to regulate it, they will only accept Bitcoin as property and taxed it. To be honest it doesn't make harm to the country since Bitcoin isn't a legal tender similar like how precious metal it is, so accepting Bitcoin is win win situation for government. Banning Bitcoin in order to make their citizens safe from high volatility isn't enough, no one can stop decentralization.
Actually in some countries it seems the government has regulated it without having to make Bitcoin a legal tender,
Bitcoin is one of the promising assets and currently its development is extraordinary,
no one expected the price of Bitcoin to be like it is today and of course the government is here to regulate it