Your question slightly misrepresents what the article says: Yes, the judge denied the motion which led to the collapse of the case, he did not make a ruling on the substance of the case.
The distinction is significant to my mind as the judge was using non-evidentiary knowledge (i.e. what he read in the paper) to make a decision on process; in this case a process that would have put a lot of people to a lot of inconvenience. It would not be proper for the judge to have used such knowledge to inform a judgement.
It is also not clear from the article if the academic paper in question was actually introduced by the defendant as evidence. If that was the case then it is only right and proper for the judge to consider it.
As to why a judge is allowed to read the news and a jury is not, I can offer several ideas:
- A judge must document their reasoning process in a judgement which is subject to review - if they were to make a decision based on matters not supported by the evidence then an appeals court could correct it. Alternatively, juries are specifically prohibited from revealing their reasoning process to anyone.
- Judges do their jobs for years, perhaps a whole career - to prohibit them from consuming media is a) unworkable and b) a serious impediment on their lifestyle. Juries are empaneled for weeks or months - such sacrifices are more reasonable.
- Judges are (supposedly) trained and impartial professionals who are more readily able to make the distinction between evidence and news.
- Newsworthy cases are relatively rare