I haven’t used the screw-mount for my Kiox (stem mount, magnet) but each rider may have a reason for mount locations. In almost 2 years I’ve never had a contact/connection issue. This may be because I’m able to remove the Kiox easily and quickly and simply wipe the contacts.(my own tether and clip). I don’t use grease or anti-corrosive paste. I don’t think I would interfere with the connection between the Kiox and mount. If you feel the need, there is a non-conducive grease available …but it could get messy if you add too much.
Besides being our own bike mechanic, we are becoming electricians too. ?