I can't say absolutely that you will get more movement. But your pronation will be more "powerful" since your are pronating through a longer range of motion.
Your hand will pronate whether you force it or not. I don't see the problem with forcing it if it's going to happen anyway. As a mental cue, though, I would focus on finger pressure or wrist snap rather than "twist the wrist" or "twist the forearm".
Keep in mind I was just describing how Webb throws it. Everyone throws the sinker differently and still achieve the same movement.