As I didn't have any such lenses with me, this is a little speculative on my part. There is a stop-down lever inside the FTZ adapter but no aperture follower. Thus the camera assumes either the lens has a CPU and can be controlled from the camera side (valid for all AF/AFI/AIP/AFS/G/P/E and CPU-modified lenses), or it is entered in the non-CPU list (and selected therefrom), or (and this is the speculative part) it will confuse the camera's meter as the Z thinks the lens is set wide open thus meters at full aperture, but the aperture will close to the set (and unknown) value when the exposure is made.
If the camera assumes the lens is AI-S, you could set the aperture via the camera - the lens would need to be set to minimum aperture (eg f22) so the full range of apertures is available. But this wouldn't be practical for AI and pre-Ai lenses with the non-linear aperture action.
Another possibility is that the camera assumes the lens is AI-S, when the picture is taken the camera stops the lens down, takes another stopped-down meter reading and adjusts the shutter speed (or ISO) to compensate for any discrepancy. This is how the FA worked with AI lenses.
Of the adapter somehow disables the mechanical aperture linkage when non-CPU lenses are used so pure stop-down metering (using the lens aperture ring) is possible - permanent full-time DOF preview.
Will be interesting to see how the camera/adapter actually work with AI and pre-AI lenses...