I do even think the opposite way, if government support bitcoin instead fiat then it wont be good for bitcoin. The statement means that fiat is replaced by bitcoin, it means that bitcoin should have stable value to replace fiat. Otherwise, it will give bad effects for the economical condition of the country if the price is not stable. People may become very poor once bitcoin price drops so bad, of course people may become richer once its price raise significantly. Volatility of bitcoin price is dangerous to be used to replace fiat currency.