Not really, because a roller coaster doesn’t transport a payload from A to B, it only transports a payload from A to A in a loop

How does this have to do with his theory in any way? In a rocket, (or even a nuclear rocket, for that matter) the propulsion is technically still WITHIN the vehicle, as it is attached to the vehicle, and is a fixed distance away from the cabin or payload (unless the propulsion module is ejected). However, in an…