I never have given diversity a thought when it comes to where I live. I care about the crime rate, the amenities of the community and the area, and conveniences, access to health care, maybe transportation, affordability, natural beauty, peace and quiet, closeness to family, as well as if the people living there- whoever they may be- are nice and not rif raf.
Where we are moving, there are people of all backgrounds- even though most are Caucasian- Irish, Scottish, Italians, French Canadian, and many others I am sure, and many from NY and Massachusetts and Florida and other states. That is diversity.
In terms of who decides to move to a 55+ retirement community, it just could be a cultural thing in the decision making for that. Maybe some people/cultures like a more urban environment. Maybe they like living with several generations in a home, which you cannot do in a 55+ community. Maybe they don't care about diversity either. I doubt there is any blatant discrimination going on, though of course, it is possible in some places. If you have the greenbacks to move somewhere, you are in.