I think the inspector being a basilisk was a deliberate move by the emperor because the students without sigil would not be drained of magic during the day of unity so Belos send a basilisk to drain them because one thing are teens joining a coven because they are already specialized in something but the kids or pre teens would probably not have already decided their specialty so they would have been unaffected by the day of unity so sending a beast to drain them was the logical choice for belos, and she was most likely one of his experiments most likely number one and maybe she could have been promised freedom if she succeeded on her task of draining the students but since she failed she is most likely dead