... or run a much lighter train with a modern locomotive. I have no doubt that a train could move passengers from Winnipeg to Churchill with less CO2 emissions than an ATR72 aircraft if that was a goal. Running trains made up of two older locomotives from the 1980s pulling steel train cars from 1950s isn't going to give you impressive numbers. They built those rail cars back when they were manufacturing the Lockheed L-1049 Super Constellation. If VIA Rail was to set goals of carbon footprint reduction and was given the money to make the fleet replacements necessary to achieve that goal they would be in a good place to deliver because the one clear truth is that the rolling resistance of rail (properly maintained), the typical low gradients on rail lines, and the scalability to add and remove cars as required make it easier to green than most modes.
On the economics side... they probably need to run the restaurant, lounge cars, sleepers, etc to make the train more profitable (really less loss because they don't break even) than if they ran the services with a few coach cars. Still, the train to Churchill with a sleeper is cheaper than the plane... suffer in coach and save a month in rent in Winnipeg.
Railfans are like a man with hammer who sees every problem as a nail. Not every single city pair needs rail service. And given how fast short haul electric passenger planes are coming along, the business case for a lot of these Western Canadian routes that are thin on demand, will be gone in about 15 years. Capital needs to be focused on the highest demand and some strategic corridors.