They also admitted his bon mot about them not having to make sure he came down from the scaffold without hurting himself.
I think I can see why – the scene as it plays shows his calm and dignity. The lines they give him (“Be not afraid of your office,” he tells the headman,“You send me to God.” “Are you so sure of that, Sir Thomas?” “He will not refuse one so blithe to go to him.”) underscore this. The line about tripping would seem out of place, and he’d have to explain the line about the beard.