When TC announced the Energy East project in August 2013, oil was and had been in the 100 dollar range for several years, the spread between Brent and WTI was $10 or more for the prior year, and Alberta's oil was being steeply discounted in the US.

The fact that oil was at $50 and the spreads had vanished when they completed their NEB filing 3 years later doesn't prove they ever thought the pipeline was viable in those conditions, but rather they still hoped conditions would change, which they haven't still.