Esther was taken against her will, despite the fact that she was well-hidden. In Targum Sheini’s commentary-embedded translation of this verse, it writes that
When Mordechai heard that virgins were sought to be taken, he took Esther into the house. And he hid her inside a room. He was concerned that the messengers of the king would see her…When they came to look for Esther and could not find her, they informed the king. Then the decree came out from the king that any girl hiding from the king would be killed. When Mordechai heard of this decree of the king, he became afraid and took her out to the market, and Esther was taken.
The M’nos HaLevi asks why Mordechai would take her out into the market after taking such pains to keep her hidden. He answers that a Mishnah in Terumos (8:11) discusses a situation in which a Kohen is accosted by gangsters who want to sully his sanctified food. Obviously, he should not risk his life, but should he hand it over? Rabbi Yehudah says the Kohen should put it on a rock, and not hand it over directly. Similarly, Esther, a holy person, was about to become spiritually sullied. Instead of performing an action of giving her over to the king, Mordechai took Esther to the public marketplace, and allowed for her to be taken passively if such was the will of H-Shem.