“Medium of communication” has its ordinary meaning and includes, but is not limited to, any newspaper, magazine or other periodical, book, pamphlet, news service, wire service, news or feature syndicate, broadcast station or network, or cable television system.
Apparently, the judge didn't spot the "but is not limited to" part of that definition.
(The text of the relevant laws: http://www.leg.state.or.us/ors/044.html)
He could have easily said that she is part of the media, but that the law doesn't protect those in the media from these types of lawsuits. Reading the law, I think blogging does fall into the category that gives it protection, even if those protections wouldn't have made a difference in this case.