Ottawa's situation is similar in some regards, but different in others. Their timing was good, whereas right now we're relying on an Ontario government that's already cut their funding commitment in half. Give them an opening, and the rest might go too. A recessionary climate changes everything.
The biggest difference, though, is that TC is a more comprehensive plan that contains several lines. Is it really worth jeopardizing the Eglinton line, which will be huge for the city, to get a subway extension to Scarborough Town Centre? Yes, the SELRT-to-subway transfer will be an odd quirk in the system, but really so bad that we should risk losing out on the other benefits TC will bring (particularly Eglinton)?