So Killer did one shot Zoro because he made Zoro faint. Hawkins was not one shot. You are saying he survived thanks to his own powers? Lmao. So that is not one shot right.
About Hawkins, he technically didn't fall this is right, but it would have been a matter of time. He lost a life and felt pretty harmless. If you don't want to take it literal, then yes he wasn't one shot, yet Oda clearly portrayed Zoro's absolute superiority over the man.