Piezo saddles work on pressure, so I believe it shouldn't make any difference.
Anyway, I didn't use it on the saddle itself... I used it at the friction point behind the saddle.
Sorry to bring this thread back again, but can anyone else confirm if nut sauce can be used on piezo saddles without affecting the tone/output? I don't have severe stability problems anymore, but I just want to be thorough during my next setup and thinking of lubing these up too...