The YYZ AC is no reason just to visit that airport.
My point is that if the counter is too busy, the AC should be able to handle ticketing.
I certainly wouldn't be relying on a tight departure time and getting the tickets. Too risky. Indeed, with AA now bouncing CCs that are billed in non local countries, I'd have lots of time on my side and plenty of "Plan Bs".
The only report we have of insistence on a CC with an in-country billing address is for South Africa. The poster mentioned a plan of arriving in YYZ, purchasing the ticket on arrival, and departing the following day. That should be doable. In an emergency, there are travel agents in town that can issue RTWs.