Narcissa was surprised, but it seemed like that Marchbanks wanted save herself from the shame that she could have caused, if she stayed and didn’t make this move. It could have also costed the house Marchbank their nobility. She found the move very smart and also noble, because this was the only way to get out of this mess. The testers were trying not to panic, because Griselda was abandoning them and the worst thing was that she wouldn’t protect them from this. They looked to the headmaster, but Albus was completely shocked of what Griselda had done and couldn't find any arguments. The testers threw a defeated look, when they had seen the angry looks from the other members of the Wizengamot. All the confidence at the beginning was destroyed. They knew that this would end up very bad.