There is already a lack of transparency from the beginning that could allow for a total centralization of the currency.

In the article he says his reason for wanting to create a currency is due to difficulty in converting his national currency to other fiats, I don't see how investing $6 billion to build a city and creating a centralized currency whose value would be largely controlled and manipulated would solve that.
He could have promoted the adoption of Bitcoin within his community and encourage merchants to accept it.