Zoro would never get bullied this badly to a opponent weaker than him because he's not a total cuck. Only someone stronger than him would, and anyone stronger than Zoro would mop the floor with Robin or anyone that isn't Luffy. Thus no, Zoro wouldn't call for their help because they would just get killed. any opponent he can't handle, they can't too. Have nothing to doo with trust, he's the fucking fighter of the crew