He is indeed Suzerain of both City-States.
*Goes full Sherlock* If you look at the provided screenshot, to the north of Sendai there is a Quadrireme belonging to a Scientific City-State. You can see the Tiles around it without the Fog of War without any nearby Units of the OP. This provides evidence to the OP being Suzerain of said City-State. If you look to the right, you can also see Rapa Nui and all of the Tiles it and its Units can see. Given that the same example was applied to the Quadrireme, we can draw the assumption that Rapa Nui is a City-State the OP is Suzerain of. THEREFORE-ok, I'll stop.