You did indeed fall through the floor of Skyhold. You then found the Easter Egg musical hat, that is supposed to be there. Then you reloaded and founf the Quizquisition guy in the vault, but without the perk to get it, Skyhold does not have a vault so, you found him in a location you were not supposed to find him, thus he did not begin the QuizQuisition with you. Find him again elsewhere and, he might have a trivia game for you to play.
