Well...everyone seems to have interpreted John Mueller's comments as confirming that it is a quality update anyway. If you're wondering what Illyes and Mueller had to say, take a look at this SE Roundtable story.
Illyes says that it was indeed an update, "Why would we deny that," in a tweet. And in a Webmaster hangout, John Mueller answered a question about Fred by basically saying that those impacted should look at the quality of their site. He doesn't explicitly call it a quality update, though. "...there is no simple kind of answer, like there is no meta tag that would make your web site higher quality...And ideally, don't just like tweak things to kind of subtly improve the quality to see if you can get a little higher. Really take a stab at it and try to figure out what you can do to make a significant dent in the quality of the site overall."
There's a good discussion of Fred on WebmasterWorld as well. The most compelling interpretation I've heard so far is that Fred is taking the place that old Panda used to occupy, before it was automated. I believe Google mentioned that something like this would happen, no? Didn't they say, when Panda was automated, that the spam team would be looking harder at websites and still handing out penalties? Perhaps Fred is just a result of those "hard looks." I'm not sure why everyone is so surprised, honestly.