Ok... let's talk about that
Saturn exploded people's heads when they were told not to look at him, but each time they did it he did some weird shit with his eye.
Later... he was making a very similar action against people like Sanji, Bonney, and Luffy. He hit them all with an invisible force that pegged their head the same way the other move did except their heads didn't explode. I assume they can take that hit because they're stronger than normal people, BUT Chopper, Nami, Robin, Usopp, and Brook are not nearly that strong. If they take the same hit that Sanji, Bonney, and Luffy did - they're probably getting their head either exploded or they're getting knocked out.