I understand where you're coming from; it would be interesting to see it used again simply to reinforce the notion that the Lieutenant Governor isn't simply a mouthpiece for the Premier (although in the case of the throne speech, he certainly is aside from any comments he wishes to add at the very beginning).
However, it isn't "my government". Perhaps in the provinces' case because the Queen doesn't form part of the provincial legislatures, but certainly at the federal level it isn't the governor general's government.
If I'm not mistaken, the Ontario throne speech before this one made use of "our government", which could be understood to be an exercise of the "Royal we". Nonetheless, it could have had something to do with the majority government at the time.