There's a difference between evil men and pirates.
Tashigi deems pirates as evil, but not all pirates all evil.
So Tashigi will leave WB's Bisento alone, Mihawk is not a bad guy so Tashigi won't go after him. Zoro is a good guy in which Tashigi will acknowledge him later on.
Or,
Tashigi requests WSS Zoro to help her gets every Meito in the world lmao.