First of all, I personally do not agree with the idea of the government using Bitcoin as a federal reserve, but if it's actually being used, that's when we can see if it''s going to help the economy at large or not. But so far, I believe that Bitcoin has contributed to the financial growth of a lot of individuals, that ouldn't have been able to gain such financial profit if Bitcoin were not there, but their Bitcoin investment yielded such a lot of profit that they were able to establish a big business or company that helped in creating job opportunities for other citizens. That's to say that Bitcoin is never useless to the economy. 

Well, there's nothing anti Bitcoiners can say against Bitcoin just to discourage some people from Bitcoin. What the economist forgot to mention is that the highest rate of money laundering was committed with fiat money and not Bitcoin.