Sorry, currently you can't hide objects for the reflected/refracted rays. This feature is only available for the primary camera rays and for the shadows.
The workaround could be render two passes, one with the torus and other with the closed object, and compose them in post, or try to add an internal sphere around the torus mapped with the environment texture and hidden for the camera and shadows rays. Anyway, the solution is not easy. Sorry for that.
Computer Graphics Software Developer
Octane plugin development and support: LightWave and Houdini