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? 

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.

First of all to have an outlier you need several samples, not just one sample as was the case in Slovakia. Secondly to have a Slovak population label most other genetic scientists would wait until they have several other individuals rather than giving it on the basis of one. The dodecad project for example requires a minimum of 5 people before creating a population reference group.

Secondly yes an outlier is an extreme that deviates from the mean however there is a limit to them as well. When it is no longer an outlier but should not even be part of that sample. For example in Eurogenes in order to get the country label ie SK1, SK2, SK3, etc…. for Slovakia the individual must be within a certain range from the mean. Meaning a "Russian" that clusters with Greeks on Eurogenes would likely not get the RU label, as it is safe to assume that they are not an ethnic Russian. Not to mention you must know the ancestry of your participants. This "Slovak" should have been omitted, as I will repeat myself once more they are likely not a Slovak, likewise with the "Serbs/Yugoslavs" whom ever they maybe, which cluster with Greeks.

Once again these are some very basic errors this scientist made. Creating populations based on a single sample and not including only people of that specific ethnicity in the sample. IT does not take a scientist to see that this is wrong.