If tomorrow you were to find in a reproducible experiment that people with samoans origins are not good at abstract math you would be "stigmatizing" the population and your research would be banned.
The problem with the word "stigmatize" is that it is a code word that draws a line of what may be studied and published.
It is basically a warning to steer clear of anything "controversial" because at any time it could be declared at "stigmatizing" and there would be no recourse.