Clause 16.1.c is written below.
Law enforcement and investigations Enquêtes
16 (1) The head of a government institution may refuse To disclose any record requested under this Act that contains plans for specific lawful investigations;
(c) information the disclosure of which could reason-
ably be expected to be injurious to the enforcement of
any law of Canada or a province or the conduct of law-
ful investigations, including, without restricting the
generality of the foregoing, any such information
(i) relating to the existence or nature of a particular
investigation,
(ii) that would reveal the identity of a confidential
source of information, or
(iii) that was obtained or prepared in the course of
an investigation; or
So basically it protects sharing of information about an investigation by an officer which is ongoing or planned and is permitted by law.
The pages you mentioned will have missing information and that is what the investigation is about.
As you earlier were saying... Probably about the job credentials. This could be related to paper scrutiny, actually calling the employer if it is found to be about the job you said about.
Contact the employer and tell that a call or email might come for reference check. The most important things for employer to remember are, period of job, job duties, full time or part time and salary amount.