"If Canadian crude isn't being transported into the U.S. via the pipeline, it's being transported via rail, and Buffett's Burlington Northern Santa Fe railway business continues to thrive."

Not so.  Transport capability limits production.  Rail acts as a bottleneck ; it can't possibly transport as much or as efficiently as a pipeline.  That's the whole point of opposition to Keystone: don't encourage even more hydrocarbon production and use.  Help force the move toward renewables (which will hurt Buffett's railway interest, too).  

Marsden is so tendentious she isn't even worth reading.