No, he was governor of the Bank of Canada during Harper's tenure. That's not at all the same as being Trudeau's economic advisor. The Bank of Canada deals with monetary policy only, not fiscal policy.
The governor of the Bank of Canada is also appointed by the board of directors, not the Prime Minister (the deputy finance minister is on the board, but does not get a vote in this matter). Cabinet can theoretically veto an appointment if they really wanted to, but in practice never does.