Sure. I'm obviously not going to address the details of the cases you're referring to. I am aware of one of them in particular.
With respect to entry at the port of entry, the admissibility determination is done by the Canada Border Services Agency based on information and instruction from PHAC. It depends on what happens at the border and what type of information is provided to that officer to enable them to render their decision. Once that officer, the BSO, renders a decision, that decision stands.
If there is supplemental information and so forth, that could have been provided to CBSA or to PHAC, but the admissibility determination is made by another government department.