All he is saying is that the demographics are heavily skewed, which is typically considered unusual. The ideal being an area that is representative of the population at large.
An example of how this plays out is demonstrated in the article itself. The author says '80% asian-american' rather than 'asian neighborhood.'
From a political correctness perspective, people in the US don't want to be seen perpetuating anything that could be considered a form of segregation. Simultaneously it is considered negative to be seen as 'gentrifying' a neighborhood, i.e. disrupting the traditional demographics of a neighborhood.