Some problems with your argument:

1. You can not argue that pre-segregation and post-integration schools are the equivalent. There are material differences in community structure, community diversity vis-a-vi class, and society in general.

2. The problem is not inherently moral. For example, a business owner is not concerned about the morality of the market, but producing a product to satisfy the market. Maybe the school system should be looking for better ways to create a product that serves the demographic that they teach in instead of demanding that the demographic change to fit the product.

3. The argument against segregation is also an economic argument not simply a moral one. Segregated schools particularly for Blacks and hispanics tend to be in inner cities with less funding, teachers that are less skilled, and in general of lower quality. I don’t think anyone would argue that kids can’t get a good education in a mono race school, think about rural communities in America. But our segregation tends to occur along economic lines and school quality.