Military occupy 600 rooms in Marriot Hotel Sydney-WHY?

Is the Australian government preparing to invade its own city? Who are the troops supposed to be fighting? Protesters? Construction workers? Nurses? Why are taxpayers paying for $600/night hotel rooms for ADF troops? Aussie Cossack, aka Simeon Boykoff, wonders what the heck is going on and why these military personnel aren’t housed at Holdsworth Army Barracks?