I might be wrong but I was informed that the WWP99 did not apply to canadian vehicles. I came across this when trying to get external coolant leak covered on a subaru for a customer of mine and it turned out the vehicle he owned was originally from Canada. He was under the 100k mark but because the vehicle was canadian and the wwp99 not applied to the VIN, he had to pay for the repairs. I would suspect the same would be in your case.
Since the information your reading states "To 100,000 miles" its pretty clear its an american thing. Your car being canadian is in KM. Best bet would be to call Subaru of Canada and talk to them. Its not even a decision any more that a dealership can make for you. Plus you would need to provide proof the vehicle has been properly maintained and that its coolant system has had its recommended flushes done. Here in the states (in alaska at least) its every 30,000 miles. PLUS the WWP99 is to have the conditioner applied even if the vehicle is already leaking. Then if the leak returns, a repair is considered/performed. In your case, you'd have to have it applied and who knows when/if the leak might return. By then they still might deny it. Call Subaru of Canada.
Good luck but I would not be surprised you'll be paying for this one. Its about a 10hr job and a couple hundred $$ in parts.