I think I need to respectfully disagree. My only knowledge of the event is from this thread and the video that was posted with the person shouting "Fire". However, you could see as soon as the monkey looked over towards the smoking float, there was a lot more smoke there than it should have been. Right then and there the show should have been halted. Instead, the show continued on and Timon's song started playing. Even after they stopped the song, they played instrumental music instead of the message advising guests the show was being stopped. With a theater that size which takes quite some time to empty out, the show should have been halted and evacuation should have started a lot sooner. God forbid it was a real fire, it could have quickly gotten out of control and caused a much more worrisome situation.
In essence, guests may complain but it's better to stop the show and evacuate rather than try and continue the show and stop it only when guests start self-evacuating.