>This is precisely the issue that the social sciences often miss because it's an ethical, not scientific, question.
You're completely missing the point - if it doesn't get results, they're not going to do it regardless of whether it's morally acceptable or not. Businesses care about results.
With all due respect (truly!), you are missing the point.
The point is: scientific arguments fail to convince because the issue escapes the scientific domain. The question is not "do we naturally tend to do X, Y or Z", but rather "at what point and to what extent are we ethically obligated to seek out people different from ourselves?"
You're completely missing the point - if it doesn't get results, they're not going to do it regardless of whether it's morally acceptable or not. Businesses care about results.