That "Slovak" is not an outlier, seeing as they are not a Slovak to begin with. In the Eurogenes or Dodecad project they would have never gotten an SK label because they are way to far from where Slovaks logically should be. If I had to hazard a guess I would assume that individual is a *** from Slovakia. Furthermore it is a very poor sampling technique to not ask what the 4 grandparents of each individual are.

The supplemntary material states in plain English there are outliers in Slovakia and Russia.  Do you know the definition of an outlier let alone commenting on poor sampling techniques of a scientist and his colleagues who published extensively on the subject? 

As far as geography goes, look at what they labelled as YG and RS on the European map in the corner of their genetic map. Likewise Yugoslavia was long gone by 2008, which a two second google search can reveal to anyone. I would assume that the editiors and publishers of a peer reviewed journal should possess some basic general knowledge about the geography of the continent that they are studying.

The study is specific to Lusatian Sorbs. Even if most your least favourite ethnicities are removed from the map it would not have made any difference to the context of the study.