So why did Labour edit it? I would say for the same reason that conspiracy theories work, sow a seed of doubt or an idea and some people accept it as the truth.
I think you and David Seymour are getting a bit hysterical and over-reacting when you describe the situation as scandalous. There are political scandals and this is not one of them.
One of the scandalous pictures is still on David Seymour’s Facebook page. How come he can display it and not the Labour Party? Free speech for him and not for Jacinda? Or on his Facebook page it reinforces a negative view of the Prime Minister, so that is okay? Same picture, different meaning in a different context.
https://www.facebook.com/davidseymourACT/