Wrong again. The Lufthansa Group knows that Lufthansa can't beat Brussels Airlines' experience in Africa, hence the group leaves that market share for Brussels Airlines. And at the end of the day, their profit comes to the group too.
If they want a presence in Africa, they can enhance their partnership with Ethiopian Airlines, for East and Central Africa. They is already a strong partnership between Lufthansa and Ethiopian Airlines. Some Ethiopian Airlines flights, in Africa are operated in code share with Lufhansa. They are up to 2 flights a day between Frankfurt and Addis Ababa. A daily service operated by Ethiopian and a 5 weekly service operated by Lufthansa.
Ethiopian Airlines has also code share agreement with Austrian Airlines
For West Africa, there is TAP Air Portugal. They serve Senegal, Ghana, Bissau Guinea, Sao Tome, Ivory Coast, Guinea Conakry, Cabo Verde, Togo and they planned to serve Mauritania, in 2018. I won't be suprised, if they add more destinations in West Africa, such as Mali
I remmember that Brussels Airlines ceased its code share deals with Ethiopian Airlines, few years ago