Broadcast rights are probably neither here nor there.
Copyright law gives me certain rights to make copies for home use. Optus is no more entitled to copy "on my behalf" than they are to vote on my behalf. Just because I can do something doesn't mean Optus can do it for me, even if the end result is roughly the same thing. The mechanism by which the end result is achieved is important because it's precisely the mechanism (ie the act of copying) that the law addresses.
I don't understand what Optus is doing. If they win then they will have no long term competitive advantage because their competitors could then do it too. It seems to be all risk with no real reward.
Worse still, not only are they risking themselves but they risk damaging regular people too. The law they are trying to use clearly intends to allow people reasonable rights for themselves in their own homes, not support commercial copying. If the court ultimately does somehow come down on their side (difficult to imagine but anything is possible) then it won't be long before copyright law is altered to close the loophole. Any change to the law (no doubt made with "industry input") to stop what Optus is doing might tread on peoples rights too. (Eg is the law specifically addressed transmission that might stop me legally being able to push content from my own PVR to my own phone).
Optus is no friend of the people here, they are just trying to make a quick buck.