Jimbe blocks Rankyaku with Haki. Drops Haki. Reactivates Haki, holds it up to the camera so it's emphasized in the panel. And then he says: "Should I call this Iron Body?" not should I call "that" Iron Body?
(Also, where on his page does Who's Who block a Rankyaku? All he does is fall to the ground and transform)
The next chapter, Who's Who uses Tekkai, we see the Haki Aura gathering around him. Then he jumps with Fang Flash. Obviously Tekkai:Fang Flash. Only thing that changes is his teeth. We already know that people call Armament Haki different things, heck Jinbei calls his one Shark Skin.
In addition, you can see th Haki Sound Effect when he says "Iron Body"
Even Greg, editor for Shueshia, was shocked to hear that people were debating this when he said it should have been obvious.