No, he’s actually not wrong. It depends on certain departments and agency. My DND clearances were not recognized when I went to another department. And as a reservist working at DND I had two clearances lol. They actually made me do a new one when I joined as a PS lol even though I had one as a CAF member.
It would be transferable at some departments but not at others. I had heard talk about standardizing security clearances for departments that deal in public safety, defence etc but no clue where that might be at.
I’m sure if you went to agriculture Canada or environment Canada your security clearance could be ported but I can guarantee it will not be ported to places like CSIS, RCMP, CSE etc