Traduciendo paso 11
This seems less like a SIM eject hole and more like a Rube Goldberg machine. The SIM eject tool pushes on a plastic pin, that pushes a metal pin, which in turn, ejects the SIM tray.
...but really it's just one more defense against the inevitable toilet tumble.
And for extra credit, Apple added a rubber gasket around the SIM tray, too!