The problem is, whatever parliament says, it can subsequently depart from. Doesn’t matter who said what at the time of the WA. Parliament has the legislative ability to change its mind, in essence.
We have a very recent example of the difficulties in an earlier parliament trying to limit what a later parliament can do. The fixed term parliament act specifically provided that you need a 2/3 majority of MPs to hold an early election. As became clear in the dog days of the last parliament, that was incapable of preventing a one line act saying ‘we’re having an election in December’ from being passed with a simple majority.
the point is, if parliament chooses to ignore the provisions of the WA, there is bugger all anyone else, the courts included, can do about it. that is not to say however that it can do so without there being real world consequences.
By the way, your last paragraph reads to me like you’re saying “I trust this government not to be a complete bunch of cunts”.
Speaking for myself, I don’t trust them that much.