I'm not surprised this has happened, more surprised that it took so long.
The reasoning by it is that Nigerian gangs are a problem in south africa. If aliens where to land here, of coarse the local gangs would try to make a profit, be it though weapons, food or interspecies prostitution. The cannabilism part could be seen as a direct hit at Nigerians but gangs have been known to do terrible stuff like this. If they had a reason, such as the ability to use incredible weapons then yes, maybe some of these gangs would turn to cannabalism (if you can call it that, they are from another planet after all).
It's a difficult thing, as the film does make references to voodoo rituals from Nigerias past and there is no mention of any other gangs. But is it enough to have what can only be described as a hissy fit? No, of coarse not. I wish people would just grow up sometimes.
