Are you "a website or part of a website", that publishes "content that reports, investigates or explains current issues or events of interest to Australians"? Congratulations, according to the NMBC you are a "news source" and therefore a "news business".
Platforms like Facebook are to be required to treat every "news business" "without differentiation" under the NMBC, in regard to a number of things (including whether or not you are "registered" under the NMBC).
Here's the rub: communication can take any form. There's an argument to be made that every Australian who posts on Facebook is a "news business" until proven otherwise.
... and the simplest way to avoid differentiation is to block everyone.
... and if only the Government were this forthcoming with protections for journalists!
Circuits, code, cities, choir.