NSW Police have jurisdiction and control for this type of declared emergency, AFP would provide counter terrorism response.
Sydney Airport Corporation facilitates the emergency response to the responding authorities.
...and for what it's worth Menzies provided the stairs, MH is their contract.
I think everyone knows and should understand that in this type of emergency the response has to be measured and there are well practiced procedures in place.
Unfortunately, Joe and Josephine Average hate having their day disrupted, they just want to board and get to their next destination, no thought that there are a couple of hundred people locked in that metal tube, thinking that this could possibly be the last few hours on the planet.
The final outcome is all the proof that our systems and safeguards are working!