The only way this could have happened is with the cooperation of someone within the National Press Club of Australia.
Getting access to the projector screen and having time to put the sign onto that screen is not a task of mere minutes and easy access. Someone, within the NPCoA, has to have given access to the room and given access to the projector screen, before anyone else had access.
This is (yet more) proof positive that Australia's media is politically biased, that Australia's news media is part of an elitist cabal that dislikes and will openly attack average Australians.
I said to someone last night, I bet the National Press Club will allow protesters to ambush Pauline Hanson during her speech and pretend they didn’t know.
Within 10 minutes, a banner reading “I oppose a pay rise for workers” randomly drops from the ceiling.