I don't agree this will affect Shortens position nor will it affect Labor's polling, sadly.
History shows that Labor supporters give "rusted on" a whole new literal meaning. They also have the attention span of fruit flies. Most will have forgotten by next week.
I guarantee that within a few weeks the usual Labor cheer squad here on HC will be reinventing history and claiming Labor never had a hard, fixed 50% target. They did it with the GFC and Swan "saving" the nation ...... turned history on its head.