Luffy and Zoro's entrance clearly drew everyone's attention, but were either of them the type to get stage fright? Did they care what other people thought? Obviously not!
They had clearly spotted Nami and the others as well. Luffy turned and gave them his signature goofy grin, but the very next second, he spotted Camie on the stage.
"Camie! I finally found you!"
Luffy shouted, then ran straight toward Camie without a second thought. He clearly intended to throw the whole auction into chaos and rescue her by force.
At this, Nami and the other Straw Hat Pirates looked stunned, but none of them stepped forward to stop Luffy. Even though they knew his actions were certain to offend the Celestial Dragons, he was their captain. So although they often resisted his choices, and those choices put them through endless misery even more often, they supported every decision he made unconditionally!
In a pirate crew, the captain had the final say! Of course, that only worked for a captain acknowledged by every member. Luffy was just such a captain: all his companions had stayed with the crew because of him.
But while the Straw Hat Pirates did not stop Luffy, someone else did. That someone was Hachi.
Hachi might have been unfamiliar to everyone. Of course, all this had happened back in the beginner area. He was a character who had appeared when Nami was recruited, only he had been a villain then, a member of the pirate crew oppressing the village where Nami had grown up.
Technically, though, Hachi had only been following his captain's orders, and he was not bad by nature. After Luffy and the others defeated his crew and he escaped from the Marines, he had come to the Sabaody Archipelago and opened a takoyaki shop.