The BIG question is: what did and how did the Creator make this world for us to live, did he not separate the races to start with and IF so there was and is a VERY good reason for that. We integrate to our own hurt, and we will rue the day that we went down this 'modern' road of integration. The author has a good point that they had to make a LAW to make it happen, we as a people did not want it by instinct.
Your argument is circular. Because the world is "ever-integrating," segregation has no role. What strength do we derive from the integration? Has it evolved to our advantage? I can cite numerous cases of its deleterious side effects, but am quite at a loss to find corresponding benefits. That it's happening doesn't mean it SHOULD happen.