A couple of thoughts on the methodology:
- A judge's marks being an outlier is not evidence in and of itself of that judge being biased. The author's explanation that "outlier scores only “count against” judges if they align with expected patterns of nationalistic bias" doesn't make any sense, because it sounds like s/he is only including outlier scores when those conform to his/her theory that there is national bias.
- Calculating a judge's scores for the same skater across multiple competitions is meaningless, because a skater doesn't perform identically all the time. A judge's score for a skater might vary across time because the quality of the skater's performance varies, not because the judge is biased for or against that particular skater.
- The analysis only looks at the "top" federations, i.e. those with the most judges. IIRC some of the most blatant examples of cheating judges in recent years have been judges from smaller federations - federations that have a lot to gain (e.g. assignments to more competitions) by having their skaters do well. The analysis should include all judges if the author really wants to see whether there is national bias.
- Maybe a biased judge is going to be a biased judge no matter what country they judge for. IMO the problem is that there is biased judging at all, regardless of whether it's nationalistic bias, helping-out-a-coach-friend bias, gender bias, anti-Carmen bias, whatever. I'm not convinced that a focus on nationalistic bias alone is really getting at the problem of biased judging.