He said she was the head of state. I don't know how this disproves the point that the queen has no legislative or executive powers in the Canadian government
The Sovereign may recall the Governor General, or request that their Governor General dissolve Parliament and call an election and the Governor General is compelled to comply.
Ultimately, all legislation requires Royal Assent, and all executive powers are granted by the authority of the Sovereign, who may revoke them at their will and so force an election.