I think this is a great example of how well Erik manages to control the context of whatever scene he’s in. The first time he turns up in the palace, T’Challa tries to shut down his challenge to the throne by referring to him as an American chaos operative, but Erik turns it around on him by announcing his Wakandan name and heritage in xhosa, recontextualizing himself as a rightful Wakandan challenger.
Here T’Challa is taking him at his word, addressing him as a fellow Wakandan royal whom he can legitimately challenge for the throne, and Erik turns it around on him again by responding and identifying as an American chaos operative, who feels no obligation to respect Wakandan traditions.
“We trained for a really long time doing the fight scenes. It was a big deal for us to create a character that didn’t seem like he got his strength or body or all this stuff just in a gym. We wanted [M’Baku] to feel like he’s out there training in the mountains, running around, picking up rocks, throwing… he’s psychically strong, but he’s not aesthetically concerned. You know what I mean? And that made it easier because we had a clear vision of what we wanted him to be. So that lent itself to me understanding who this character really is.”