The ReMote Pro Clamp Conversion Kit is there in case the clamp for your ReMote Pro Dropper Lever is damaged in a crash, or you’re keen to use it on another bike or with a different type of brake than it was originally designed for.
The plastic axle is deliberately made to be the weakest part of the ReMote Pro Dropper Lever, so that in the event of a crash it will give first, which means that you won’t need to replace the more costly lever. It also presents a way to broaden the use case for your existing lever.