That is quite sad. In this case you are not firing for the wrong reason.

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.

Solution is easy there -- promote away.

Please no. That might get them out of your hair (maybe), but then you've just put someone incompetent in a position where they can exercise it even further.

I think people doing this is the direct cause of some head-scratchingly awful middle managers I've had to deal with..

Most middle managers are awful though, because they get no training.

Dilbert's Principle?

If HR can't get rid of an underperforming employee because they're too lazy to do their homework, the company is fucked anyway. At least the dude is out of your hair.