I think I have answered that. The responsibility for access to information has been delegated by each minister of the crown to specifically named public servants. They're named in the delegation orders. Those delegation orders are, as far as I understand, publicly available on each department's website.
No political staff member has received a delegation of authority under the Access to Information Act; therefore no political staff member is entitled to make access to information decisions. Further, the Prime Minister's own rules in Accountable Government provide, at page 37, from which I read in French, and will read in English:
The exempt staff do not have the authority to give direction to public servants, but they can ask for information or transmit the Minister’s instructions, normally through the Deputy Minister.