Why should the US have an African policy? They can concentrate of the offshore oilfields and leave the rest to China. The mere expectation that the US has or should have an Africa policy is the first mistake.

Africa remembers the US (Clinton) failure to act on Rwanda, and the US humiliation in Mogadishu, The CIA cock-up in Angola, the failure to act on Zimbabwe and really no serious African is expecting anything from the US. So the best advice is to do the same. Don't expect any coherent policy or action from the US on Africa.
Well, USA does have an African policy. And oil is not the only natural resource of Africa, far from it.
Sorry Sir, but africa does count in a multi polar world. And serious african do expect things from USA. Not because the actual president is a black man but because USA cannot afford Somalia to exist, cannot afford Islamist to have a safe heaven on that continent. Because North Sudan is becoming the wheat plant for Arab countries and are building a power pole through religious cultural proximity. Because soon USA will have to buy Chinese iron to produce steel... (the list is not exhaustive)
There are many reasons for USA to have an African policy. But as everything, politic does not like vaccum. Therefore, there will be someone else who will take its place...