Admissibility into Canada is a decision that's made by the border officer. It's in the border officer's hands to determine admissibility. I don't think, in terms of the way you're putting it, that it is appropriate for someone to have to call their MP to exercise their right to come back into Canada. On the face of it, the answer is no.
However, I have to believe that there was some reasonable basis for detaining these people for a period of time in order to determine the background, the identity, or some other issue pertaining to one or more of them. Again, sir, I'm speculating here, and I'm loath to do that. I would like to look into the case that you've mentioned and find out what happened.