I would think that an organized group of travelers armed with blackberries could circumvent this security measure if they were trying to smuggle some items in thier luggage.

1) Have 3 or 4 people arrive at say YYZ same day prior to your flight. They relay back what code they got and if they were sent to secondary.

2) Bad-guy 1 shows up with Bad-guy 2.

3) If Bad-guy 1 ones get code for secondary he lets Bad-guy 2 exit with the bag or vice-versa.