I have to wonder where this would likely go on appeal (since it sounds like this is an initial court ruling). With that being said, I also find this ruling to be particularly bothersome insofar as Lufthansa basically succeeded by arguing that publicizing a fare which they had filed of their own free will (albeit by mistake) harmed them. Now, I understand why they made that argument, but given their obsession with tinkering with fares to maximize revenue, the rise of "flash sales" in many cases, and in many instances additionally preferring to automate the process as much as possible, a bit of caveat venditor really needs to apply. An airline making a "rational but curious" business decision isn't always easy to differentiate from one making a pricing error, and there are doubtlessly going to be cases where telling one's readers about a flash sale with limited availability is an advantage to a blogger.
With that being said, the ruling is a very narrow one. It seems to only apply to German sites, only to promoting fares as "mistake fares" (or similar phrasing), and only in cases where the site in question can seriously be claimed as a competitor to the airline. I'd be hard-pressed to see this sort of logic hold up in the US, for example (as opposed to the "hidden city" case, where you could at least argue that the website in question was encouraging passengers to break airlines' CoC and using data mined directly from the airline to do so), especially given the First Amendment.