I think the question needs to be fleshed out a bit more.
I don't think that Channel 9 audiences watching at 7pm on a weeknight could handle the reality. Which explains why we have thisHome and Away HouseBig Brother.
Channel 9 just need something that will compete with what Channel 7 are playing at the time. (Apparently there used to be a Channel 10 too but I've never seen this mythological station).
However if Big Brother were at 10pm like BBUK is (and possibly on a different channel), audiences could handle it. The main problem is that it's ingrained in Australian psyche that Big Brother is a bit of a teenybopper show. It's a shame, because it started with a small edgy, experimental element. Even though Channel 5 took over BBUK and cheapened it a bit, the experimentation element still remains. BBAU has crossed over into cheesy soap opera genre.
Yep I agree on the Australian version. The dilemma is that there basically is no tv viewing audience past 10pm in Australia.