I remember the day well. You're absolutely correct that there is the APPR tarmac rule that we follow, not just in Canada; there are other tarmac policies around the world. However, in the case of safety, if it is not safe to do or if it jeopardizes...damage or injury, we do not have to take the three hours and 45 minutes.
In this case, if you look at the number of aircraft that were in Vancouver that evening for all airlines, we could not get to a gate safely. The airport could not keep up with proper apron clearing, employees could not tow aircraft, and we could not disembark using air stairs out to an open surface and transport the passengers to the terminal. All of these were explored. All of these questions were asked.
Nobody wanted us to have customers on board for 11 hours or for any time of a lengthy delay. However, in a situation like that night's, when it is unsafe and we could jeopardize making things worse, we will always take the side of safety.