while I'm not arcticbull, I worked for a period of time with somebody who was a minority and completely horrible at their job. Everytime my boss tried to get him fired, HR pushed back
I get that HR might need to verify that this person is being fired for the right reason and that no discrimination is in play (which might happen unwittingly), but just keeping someone employed because they are a minority is not a good solution.
On a related note. If I was a minority, I would think that I was just being hired or kept on the team because I am a minority and not for my technical ability. This behaviour from HR would further encourage that thinking.
I think people doing this is the direct cause of some head-scratchingly awful middle managers I've had to deal with..