Yes, that is what the Supreme Court ruled. The ruling is a bit more complicated than the simple statement that those offices are not subject to the act.
Basically, the Supreme Court stated that the minister is not part of the department. The documents that may be in the minister's office are not completely exempt from the terms of the act. The Supreme Court developed a two-step control test. The first step consists in asking whether the records relate to a departmental matter. If the answer is no, the act does not apply to the records. If the answer is yes, another question is asked: Should a senior official of the department reasonably be able to obtain a copy of the record? If so, the record is covered by the act and can be disclosed. To determine whether a senior official should be able to obtain the requested record—my apologies, the control test is complicated—the document's content, the circumstances under which the record was created and the overall legal relationship between the government institution and the person who holds the record must be scrutinized. The test is quite complicated.
In addition, another decision by the Supreme Court concerns the commissioner's powers. Usually, I am allowed to enter and search a department's offices. I can go into a department and conduct a search. I have the power to do so. But the Supreme Court ruled that, since the minister's office does not come under the act, I do not have that right. However, I can issue a writ to compel the records located in a minister's office to be disclosed so as to ensure, for instance, that the control test was applied correctly.