What a specious article.
The obvious reason is that US forces commiting bad acts is simply more newsworthy than Saddam's thugs doing far worse acts.
If I may draw an anology, Kennealy's 'Shindler's Ark' worked because the protaganist was a Nazi, working directly against the basic tenet of Nazism.
In the same way, the grusome activities of Saddam's gangster cohorts really come as no surprise because that is what he is infamous for. We've all read horrific accounts over the years, so from the news agency's point of view there is really no story.
US soldiers abusing prisoners is big news because it is not what our armed forces are all about. It is unexpected. No news agency anywhere would pass up this story, no matter what their political bent.
There is no insidious conspiracy of left-wing media, all the papers are doing is adding value to their advertising space by increasing their circulation. To do this they print sensational stories.
"Man bites dog"
And whether they realize it or not - in doing so they are working against the good guys. I think the author is trying to communicate to other - more clueless - reporters on their own level(maybe), and for that, I think it's a good article.