Let it be based on the best person for the job. If that happens to be a black woman then fine, but the race and gender should not be a requirement at all. Saying that you will only choose a black woman is just as racist as sexist as saying you will only choose a white male.
Our medical care isn’t limitless, there is only so much we can actually do. Look at how Biden has been progressing even with the best care in the world, he clearly isn’t in the best shape and it’s only going to get worse. It’s entirely possible he gets worse fast and for there to be nothing that can be done about it even with the best care we can give him.