The incendiary atmosphere in the immediate aftermath of Tuscon probably goes a long way toward explaining why this event didn't get a lot of coverage. But more broadly (at the risk of stating the obvious), there's a certain amount of self-censorship that's gone on with regards to the domestic terrorism issue. Why? Here's a theory. While there is a segment of the media that breaks down along clear partisan lines (Fox vs. MSNBC, for example), many smaller outlets still compete for readers and viewers across a broader spectrum. As with any business in the hyper-politicized atmosphere, it pays to water down content to appeal to the widest possible audience. Given that audience is extremely polarized currently, there is a danger that investigative reporting or keeping domestic terrorism stories in the fore would lead to charges of bias and alienate customers, no matter how clinical and balanced those stories were. There are plenty of examples of such charges in every comments section of thoroughly innocuous Associated Press articles on the topic. Despite the fact that there's a clear, present, and rising danger from rightwing violence, journalism operating as a business in an environment where a significant part of the population is somewhat sympathetic to the ideas underpinning domestic terrorism, if not the actions themselves, reporting on those stories (and the broader movement) would represent a potential business liability. In a climate where "old" journalism is already in deep shit, it doesn't pay to play in minefields.