As a British Airways franchisee and oneworld affiliate, Regional Air operated from Nairobi to Asmara (Eritrea), Djibouti, Harare, Johannesburg, Khartoum, Lilongwe, Mombasa and Lusaka (Zambia). Harare, Johannesburg and Lusaka remain part of the oneworld network, through services by other member airlines.
So it looks like Johannesburg is safe, though, right? I cannot tell if they mean from NBO or not.