It's always better if a regional neighbor is the one who intervenes, in Africa or anywhere else. We should encourage the stronger, more democratic nations all over the world to start taking a hand in keeping order in their corner of the world. Japan, Vietnam and South Korea should have started down this path years ago and the African nations, especially South Africa should be helping to maintain order, and build democracies, in Africa. The US and her allies should stand ready to do the job if more help is needed, or if no one else chooses to do so.
Making the decisions to intervene is difficult and costly. But if you're going to make the decision to do it, why only go half way. You're putting yourself out there. There's no point just to go into the region, and try to help out there. Go to the source of the problem. Hopefully that will take less time, which would balance out the costs.