AFAIK, it's been the only "deviation" from YUL-CDG & YYZ-MUC, and certainly a preferable option (and responsibility of the company) to get customers home off of an aircraft that went mechanical. Although planned, it also operated Rapidair flight 420 today.

In the case of the NRT substitution, I'm guessing there would have been ample "elbow" space on the flight. The aircraft was replacing a 77W with has 100 less customers, no premium economy planned, and certain that several J customers with flexible tickets re-routed via alternate gateways.