If they meant real diversity then it would actually be a good thing, but all they mean is a diversity of color. There is plenty of diversity in a population white people, and simply adding a different color doesn't make it any more diverse in ways that are actually beneficial. There could easily be and likely is more diversity between two white people raised in different parts of the same country than between a black and a white inner city dweller. It's another one of those things where they take a statement that is potentially true and warp its meaning.