Well, it's not too effective, is it...
I've heard this nonsense before, from angry blacks with penknives to grind and neo-Nazis, who are delighted by the theory, and of course, it's arrant nonsense.
If the medical lab guys and the politicians wanted to "ethnically cleanse" Africans, they picked a slow, tedious, and ineffective way to do it. AIDS takes time, crowds hospitals, and doesn't really keep up with birth rates. Because of that time and so on, it lends itself towards exposure.
"Superflu," as written in Stephen King's The Stand, would be a lot more effective, as King fans would know.
No, the models for genocide are not by inflicting disease. Hitler set the gold standard for effective genocide, but Pol Pot and the Rwandans are not far behind in this grim, cynical, and horrific calculus of mass murder.
This "theory" is just rubbish being used by cynics and ideologues to gain attention, support, and money.