Is it called the TRG (Tactical Response Group) in NSW?
I wouldn't have thought this would be an SAS job. This is the TRG's bread and butter.
I believe the NSW unit is called the Tactical Operations Unit and are part of the larger State Protection Group. We absolutely have an SAS, although it's commonly referred to as the SAS-R to differentiate it from the British SAS upon which it is based. All of our states and territories tactical police units train with one another, and receive instruction from the SAS-R and other Military special operations units. In terms of military CT units tasked with domestic protection, we have TAG West (based in Perth) which is comprised of SAS-R soldiers, and TAG East (based in Sydney), which is comprised of 2 Commando Regiment soldiers and RAN Clearance Divers.
However, it's never a good look having the military involved in domestic issues, and as such, these units are only going to be called in as a last resort when the situation is deemed as being too advanced for the police units, such as boarding ships and the like. NSWs tac teams are more than capable of handling a man in a cafe with a shotgun and some hostages, even if he does have explosives in his possession. It's exactly what they're trained for. As I mentioned in an earlier post, these aren't your average donut eating, speed ticket issuing police officers, that have donned some body armour and picked up an assault rifle for the day.
As it stands, nobody has been hurt, and 5 hostages have made it out alive. There is no point escalating things unnecessarily at this point. If this man is known to police as has been reported, then there is probably a very good reason why they have not yet gone in.