I don't get why this study is trying to draw big conclusions through comparing stories published by mainstream news outlets and stories that are popular on social news sites heavily, heavily skewed towards geeks.

As the cliche goes... apples vs. oranges.

The guy doing the study even says this about the inherently different foci of the two:

"This technology bias was partly down to the fact that it was early adopters of technology that lead the way when it came to 'playing with the potential of the internet to empower users', said Mr Rosenstiel.