i'm going to double down on the idea that the problem here is that the pmo doesn't seem to really understand our own system of government - and that, again, it seems to be viewing itself through some kind of american prism.

so, the pm is saying things like "the decision was solely up to the minister." - and that's actually wrong. maybe it's the way things are in the united states, but not in canada.

this isn't exactly an academic source, but it's not a controversial point, either:

Ministers are responsible for ensuring that the policies developed by the Cabinet are implemented in the departments.
(https://www.ourcommons.ca/About/Compendium/ParliamentaryFramework/c_d_executivebranchgovernmentcanada-e.htm)

that's what a minister does in canada. it's not an elected office, and it's not expected to act independently of the cabinet; what it's supposed to do, rather, is carry forward with decisions that are made, collectively, at the cabinet table.

what that means is that the cabinet actually had every right to tell the minister what to do here, if it was determined to be a matter of government policy, which i believe it clearly was - they passed a law specifically for this purpose, and had the clear policy objective of preventing economic harm.

so, i don't know where this discourse is even coming from - it's not in the canadian legal tradition to argue that the attorney-general is independent of the pmo.