I can't speak with absolute authority, but I know that our screening officers, under the Quarantine Act, can refer someone to a quarantine officer under PHAC. The individuals must wait until they've been dealt with by that quarantine officer, and only at that time can they depart the CBSA hall. I would have to come back in order to be authoritative on your question.
On February 3rd, 2020. See this statement in context.