So one solution may be more government oversight?
Not oversight, but certainly regulatory barriers to this kind of backing away from customers. That in turn might change the economics a little - not enough to harm current investors, but enough to discourage wealthy investors eager to exploit a temporary weakness.
Unfortunately, I am not King. So I expect that Ottawa will look on meekly while CN goes through a difficult period of retrenchment. Maybe if it gets bad enough, someone will step in.