I suspect the AGL board realises that the value of Liddell to...

I suspect the AGL board realises that the value of Liddell to AGL - if Liddell was to be put up for sale - is vastly greater than the value that any prospective buyer might reasonably care to pay, meaning that going through a sale process would really be little more than a charade and, ultimately, an exercise in futility.

Because AGL would have to factor into the sale price the impact on increased competition for its next generation of generation assets, and the reduction in the financial returns from that capital investment.

And which buyer of Liddell in his/her right mind would be happy to pay that sort of premium to underwrite returns of AGL's capital investments currently being undertaken?

But this discussion is all a bit moot, anyway.

If a public company chooses not to divest a portion of its asset base, no legislation can force them to do so.