Apart from the spill issue, the oil sands themselves are hardly sustainable from a long term view. Harper and those he shills for may be experts at spinning or ignoring the science on climate change, but that doesn't make it go away.
One of the roadblocks he's running into in trying to get to Keystone XL rammed through is he can't control the message in the US and people there are rightfully protecting their long term interests. Large areas of North America are likely going to become much less habitable in coming decades, it's a scam to claim that we can still engage in carbon intensive activity like the oil sands and still conserve a lot of the benefit we currently enjoy from what has been a relatively benign environment. Extremes like we saw with the flooding in Calgary and Toronto are likely to become much more common as well as water scarcity and habitat change that will make some areas virtually uninhabitable.
Harper may be thinking what's best for next fiscal quarter or more likely what's going to get him elected again in 2015, but he has almost complete blinders on regarding significant changes that are already underway. It borders on the criminal to focus on such a narrow interest, we need to be looking seriously at how to move off of all fossil fuels eventually, starting with coal and unconventional oil, which are the dirtiest. It doesn't matter what the short-term economics say if the mid to long term indicate looming catastrophe, both on an economic and environmental scale.
Harper is a second generation Oil man, we really need someone who isn't stuck in that past to lead us into the future, not stampede us over a cliff which is what I think Harper and his people are doing. You don't go to the effort of taking almost complete control of the political structure of a nation while stifling free expression of information without a reason, and I think we see it here with Harper showing what his real agenda is all about. Protect the oil interests at all cost in Canada, even if that means the end of much of what makes this nation so amazing.