Several times in this article it's pointed out that the Australians who're debunking this memoir, work for a Rupert Murdoch company. It's as if this indicates they cannot be correct, since of course, Murdoch is "evil incarnate" or something of the sort.

This is a fallacious appeal to authority. It fails based on several factors:

1. Not everything that happens at every Murdoch outlet is personally orchestrated by Murdoch himself. He has people working for him. Those people have lives, credentials, expertise, motives, etc. of their own, independent of him.
2. Even if this had been orchestrated personally by Murdoch, no matter how poorly one thinks of him, it's still the case that (as the saying goes) "even a broken clock is corrrect, twice a day." If Murdoch said the sky is blue, would anyone seriously argue it?
3. While the Australian is a Murdoch company, so too is HarperCollins, which is publishing the book. If the premise is that Murdoch is personally trying to destroy the book, then ultimately he is only hurting himself, setting off a war between two of his own properties!

The truth here is in the facts that are uncovered. So far many of those facts are working against Beah and his handlers. Instead of whining that they're under attack by a ruthless and vindictive Murdoch, they should instead just 'fess up to whatever faults this memoir may have, and put the matter to rest. That, or they could produce evidence of their own to support the memoir ... which to date, they haven't done. They serve no one by attacking those who question them.

I don't think the implication is that Murdoch is personally orchestrating anything. The implication is that the vast majority of Murdoch's media outlets tend to produce salacious, sensationalistic, muckraking (in a bad way), yellow journalism. It is where he came from, and it is what makes him money, so that is the mandate of people who work for him. I automatically distrust the reporting on Fox News, the NY Post, the British tabloids, etc. (if not -- yet -- the Wall Street Journal) for this reason; when I see someone attacked in these publictions, I generally reserve judgement until I see the case made in a venue that I trust (like Slate). There's a reason why this Slate piece is an "on the one hand, on the other hand" one; if the Australian's reporters had made a strong enough case, this piece would have read very differently, since Slate certainly doesn't shy away from "takedowns" if they're justified by facts.

Exactly right. It is the environment that Murdoch creates that taints the reporting ... not everything is tainted, but it becomes difficult to trust, to tell what is and what isn't.