Perhaps, Malfoy was using her intellect and thirst for knowledge to his advantage. If he could keep her guessing long enough to want to know more, he could swoop in when she wasn't expecting it to capture her. But, she had to remind herself, couldn't he have taken her in the cellar? Assuming that there was indeed an Anti-Apparition ward surrounding the property, he could have simply Stunned her with very little effort. A portkey that he could easily obtain from the Ministry of Magic would have been all that was required to drag her back to be thrown at the feet of the Dark Lord.