Nowhere does the article say he issued a "verdict," just that he had "sided with the media companies." In this case, he sided with them against a challenge to the legitimacy of their complaint, ruling that if Cox wants to get out of this they're going to have to go with a different defense.
A preliminary ruling like this can be very helpful to both parties involved. The judge has basically told Cox's legal team, "Based on the information I have available to me right now, here is how I would rule, and why." That gives them the opportunity to build their case based on how the judge is leaning.
Judge's are not the same as jurors. They aren't sequestered, and there's no requirement that they only consider information presented at trial. At this point, the judge has read tons of material about the case. If he said he had no opinion at this time, I'd assume he was lying. Better to know where he stands, so that all parties involved can form meaningful legal strategies.