After nothing happened to Zoro and Nobody left the scene, he kept standing there bleeding heavily until Sanji showed up.
I always thought the fact that he kept standing there (menacingly) was for Oda to deliver a badass moment or because Zoro just wanted to prove a point. However, It‘s not been mentioned how long the others were knocked out but considering the damage that they took it was probably quite a while. So Zoro just kept standing there with a focused look on his face and I asked myself why didn’t he just lay down or something.
Then I realized that he was probably still on guard, protecting everyone else who were still unconscious. Because if a Shichibukai can just randomly show up, attack, nearly wipe out the crew and capture the captain, then it can happen again at any given moment that someone with hostile intention shows up like that. They were still in enemy territory and Zoro knew that as long as everyone else is unresponsive someone has to be on guard.
Even if he‘s at deaths door he has to be locked in. The crew just cannot afford being exposed and vulnerable like that. To be the last man standing to protect his crew is his responsibility, and he is going to fullfil it no matter what. I think that’s what Oda tried to show us in this scene.
