Ok,first I think you should familiarize yourself with Left-wing vs Right-wing politics and what it means. Here's a link to Wikipedia that sets it out quite simply: http://en.wikipedia.org/wiki/Left-right_politics - scroll down to the modern view of left/right as the historical viewpoint is confusing.

Basically, The contemporary left usually defines itself as promoting government regulation of business, commerce, and industry; protection of fundamental rights (especially freedom of speech and separation of church and state); and government intervention on behalf of racial, ethnic, and sexual minorities and the poor. The American right is broadly defined by upholding a traditionalist understanding of constitutional law, protection of fundamental rights, opposition to governmental regulation and income redistribution, immigration control, and opposition to "reverse discrimination".

Then you might want to check out three or four different newspapers: The Globe and Mail, the National Post, the Vancouver Sun, and the Province. Try to find one story that all four write about. You'll probably find that the Province is the most "right" and the globe and mail may present a more leftist viewpoint. Although arguably in Canada, even our leftists are pretty near centre.

Now, back to the Schreiber/Mulroney fiasco. The article is basically saying that even though it was huge breaking news back in 2003, the writers at the major newspapers in Canada got together to repress the story. I think the author is suggesting that the political viewpoints of the media moguls of the time (Conrad Black, Southam, etc.) were all conspiring to keep this a secret.

And then the article seems to suggest that if our media constantly keeps feeding us political views that are centre and right on the political spectrum, we may be more in line with the political conservatism of the US.