One does not need an expert to predict a terrible failure of Bitcoin as a legal tender and for $30-worth of free BTC wallet.
But as a minority of reserve asset, Bitcoin might be a good idea, nobody bought bitcoin at any price whatsover and wasn't able to make a profit that beats US T-bonds for 4 consecutive years (please double check on this, it's not a financial advice), let only if they DCA their portfolio.
Of course such national reserve cannot make a large % of the total reserve as the risk is also high and wealth of the nation is not meant to be used in risky bets. 4 years is also not a very meaningful window for a 16 years old market.