It's quite simple, really: Makate conceptualised the idea - he did not invent it. Vodacom began to build it. By law, MTN invented it. The likelihood that both providers came up with such a non-core service, which was quite arbitrary and unique in the market, at exactly the same times with almost identical concepts using the same terminology, is nigh on impossible.
Now put on your tin-foil hats: We know that Makate conceptualised the idea first but is not the inventor. Either Vodacom wasn't the only group he sold the idea to, or there was in all likelihood some corporate espionage going on at the time and MTN had more resources to throw at this, from both legal and dev. The fact that MTN didn't sue is a very odd one for me to accept without contemplating that they maybe, knowingly, accepted the IP from a Vodacom employee and were aware that the Vodacom employee had sold the concept to Vodacom bosses. If this is the case, it's plausible that Makate had no right to release this idea to MTN under any circumstances and MTN were aware of this. And if you look at how this has played out, everyone is a winner in the end, as VC retain profits without paying the IP holder, MTN retain rights and full IP, and Makate gets his share as well. Perhaps there's no need to stir this hornet's nest much further?