Just ro be clear, this was one state of Australia, where the local conservative party is in power. It is only one of two states (out of 8) in Australia where this is the case. The minister who denied access is using the visit as a political football to claim the prisons are underfunded and therefore cannot be presented to the UN because it will look bad.
So... he's being honest that the prisons are not up to UN standards then.
It's a very shitty, hypocritical move given how much Aussies like to play holier than thou when it comes to these things.