Ah yes. Another story arc more or less successfully closed.
And what better way to celebrate an ending than having your characters all laugh at a terrible joke?
Who knows? Maybe that timeline would have worked out well for Anne and Henry before whatever new perturbations in time caused it to be overwritten?
It is clear that, even though they come from timelines divergent from actual history, Frederick, Newton, and Peter all know the classic ending to the Anne and Henry story.