You can't disable just sensor stabilization on the Z cameras with an adapted telephoto - it's all controlled by the switch on the lens. If it's on, it's all on, if it's off, it's all off. In addition, IBIS is only partially in play on adapted lenses with VR. The lens will provide pitch and yaw compensation; the sensor only provides roll compensation.
As for VR on a tripod, if the tripod head is loose, generally you're fine with VR on, especially at slower shutter speeds. I do recommend shutting it off if the shutter speeds are high enough that you don't need the extra help. On some lenses, you'll get better acuity with it off at higher speeds, in some cases (higher-end glass) it doesn't seem to make much of a difference.