They were.

Porter said the aircraft returned to the terminal, where the passengers (as in the kid and the accompanying parent) were asked to leave the plane and their baggage was removed. The airline said the additional time required to complete those steps and refile the flight plan meant the flight could not depart before Victoria International Airport’s (YYJ) runway closed at 12:30 a.m. As a result, the flight was cancelled.

I'm surprised the family made it out of there in one piece. No jury would convict you for taking that sucker punch.