Sanji knows the life that Zoro has been living, attached to the Yakuza, but he still sees him and he never asks questions. Zoro assumes Sanji is in the dark and does things on his own. But when Zoro announces it will be their last meeting, after their 10 years, Sanji can't sit quiet anymore and let Zoro be dangered. He is more than willing to dirty his hands to "pick up" his Samurai with no sense of direction.
One Piece dj - Unwanted