It does seem possible that Virginia Giuffre and her legal team were unwilling to accept a permanent non-disclosure agreement or that a permanent NDA would have been costlier. By all accounts, the Duke of York was under enormous pressure from his family to settle the case before the Jubilee festivities.
i news has more commentary from Ms. Giuffre's attorney on the lack of a non-disclosure agreement:
https://inews.co.uk/news/virginia-g...w-still-heard-court-settlement-lawyer-1467827
Ms Giuffre’s lawyer David Boies has told i that there is nothing preventing the allegations against the Duke of York forming part of the evidence when she goes to court in her separate defamation case against Jeffrey Epstein’s former defence attorney Alan Dershowitz.
He told i: “There is no NDA or gag order that would in any way limit Prince Andrew being mentioned in the trial.”
If the Telegraph's anonymous source can be trusted, the Duke himself may not want to remain silent forever:
(I am not sure why the anonymous source mentions feelings about "the House of York", as the Duke's personal situation cannot be compared to the position of the other members of the house of York.)