On one hand, one of the main factors the Yes campaign puts forward to support a permanent change to the Constitution rather than legislating the Voice is that, if legislated, the Voice can be disbanded or significantly changed in form and purpose in future.
Correct.
On the other hand, one of the main defences to No voter concerns about permanency that Yes voters put forward is that being in the Constitution does not preclude the Voice from being changed in form and purpose in future.
Nope. You just made that up.
The Yes campaign can’t have it both ways. So, it is clear that the Voice CAN be changed in form, substance and purpose in future both if legislated as well as if enshrined in the Constitution. So, there is no down side on this front.
So you put forward something real then just made something up. This is how conspiracies work. Best lies are with a sprinkling of truth.
So, why not legislate it? This way we can all see how effectively it operates and whether it is successful and, if necessary, have a more informed referendum at a future point in time.