An American fan of EPL here-
Over here, this NFL rule has hardly raised any issues, and I'm sure many have accurate/inaccurate conceptions of USA race issues.
If an owner is willing to interview 4 candidates for the job, an extra interview with a 'minority' candidate is no extra problem.
If the owner isn't impressed-nobody cares. But this provides an opportunity for a 'minority' candidate to get a chance to impress and get the job.
There are no quotas where an owner has to give a job to a minority candidate- they just have to give one a chance in an interview. And I think the NFL has shown that once that door is opened and a minority candidate has a chance to convince an owner that he is a great option, sometimes old owners with historical prejudice are impressed with someone who might have worked twice as hard as any other candidate.
Again - it really isn't a big deal over here, in a place with perhaps far worse race relations than in Britain.
What is the downside to giving a minority candidate an interview? I completely fail to see the downside