People need to be smarter than what I see here. Black Maria is at the 3rd floor. Luffy and co are in the 2nd. Black Maria is singing up there, but Sanji stop at the 2nd and let Luffy and Jinbei jump.
Sanji is not reacting to Black Maria here, but to someone killing/bad intents with his CoO (the pattern of his face is not even the one that Sanji have when reacting to girls). Oda is setting Sanji fight by letting him alone there.