I think you'll find, Boyo, that the concept of governments being able to borrow at a low rate is very much contingent on them marinating an AAA credit rating, which in turn requires them not to borrow too much, ironically. Obviously the credit rating system is even less reliable than a state government, but that's what will determine the borrowing rate.
It seems to be very much economic models at 10 paces at the moment, as regards whether privatisation slows down the rate of cost increase, so I'll be a little more circumspect than your absolutes.
If the money could be borrowed so easily, and at less cost, why do you think Mike Baird is going down the privatisation route? It's brought several of his predecessors unstuck, and it remains very unpopular. Please don't just say ideology, because most politicians will cash in their ideologies for an easy run at the next election, which Baird is now not going to get.