How is Mary's statement that the accusations are mere pretense received

In Act III of The Crucible we see that Mary Warren has discovered some previously unseen courage. But it's been hard for her to do the right thing. She's a very weak, timid character, scared stiff of Abigail Williams, and so it's not surprising that, according to Martha Corey, she's been "strivin' with her soul all week" before finally deciding to tell the truth in open court. She's signed a deposition stating that neither she, nor any of the other girls, saw spirits. It's all just a pretense, a complete lie.
But Danforth's not happy about all this. He knows that the state's entire case is built upon the young ladies' original confessions. As far as he's concerned, the voice of heaven has been speaking through Mary Warren and the other girls. He's invested so much time and energy into the witch trials that he simply cannot let the matter rest as easily as that. Apart from anything else, accepting that the state's case is built on a total lie will make him look like a complete and utter fool, taken in by a group of young adult females and their overactive imaginations.