I'm not sure if I would agree with your categorization of nebulous sources. I think The Globe and Mail is a fairly credible organization, I don't think they put stories on the front page of their Saturday edition without verifying the veracity of those sources.
Let's go back to the article and see if you can help me understand this. The article goes on to say:
Instead, oil is being sent blindly, with no added degree of safety, and without the higher degree of transparency that Transport Canada sought with its push for more testing. The Transport Canada order “doesn’t seem to change anything,” said one [senior] industry official whose company is involved in shipping oil to Canada.
Later a former U.S. railway inspector says:
There is no requirement to test oil, despite what Transport Canada claims.
Is that true?