Just about all your points can be addressed by this: ABF in this case needed to know whether it was safe for their officers to conduct their duties. Any indication of a covid outbreak would obviously be a huge risk to the officers who have to collect the passenger cards from each disembarking passenger.

That's why they were asking for test results and were "investigating" the health status of the passengers. There's literally nothing more to it than that.

When they recieved confirmation from the ship's agent that the passengers had indeed tested negative, they asked for that in writing. What they were sent was instead FLU results. Whether that was a stuff up by the agent or the ship, it resulted in a misunderstanding and the ABF continued to do their job as usual - which is to give the all clear for the immigration and customs aspects of the disembarkation.

ABF need to step up here.

They have stepped up since day 1 when the commissioner explain the roles of the various agencies and the legislation they work under. This is not "hiding behind an excuse", it's just the facts.

It's like you're at the scene of a house fire and getting mad at the ambulance officers for not putting out the fire. No matter how much someone explains to you that it literally isn't their job, you're putting your hands over your ears and yelling about it being some big conspiracy or cover-up.