I've worked in production, but admittedly not in Australia and it could be different in this situation. There would be an extremely detailed conversation and contract with each housemate about exactly what can be shown of them and what can't. A lot of reality shows like this have had issues afterwards when people saw the footage back and didn't know exactly how much would be shown. They even negotiate what conversations would be aired. I suspect some of the girls and probably Dion made it clear from the beginning that nothing could be shown. And from a production standpoint, some of the guys were probably selected because they opted to show everything.