To reiterate, I do have respect for the view, but you actually stated the bit I find unrealistic:

There is the possibility that voting for a voice now means a treaty would lack political capital or public approval for decades to come because we already voted for a voice

I don't think the voice is an insufficient response to delay a sufficient one, and I do know what the insufficient response looks like. The reason is:

• This is driven from the statement from the heart. Having a voice is a driving force for the treaty, not a delay. It's also not a white person's consolation prize. The statement is softly spoken and expects slow and steady progress, which I believe is consistent with indigenous values.
• A no vote on a referendum is far more likely to stall out any progress on a treaty because it looks like a conservative no. This discussion isn't whether to hold a referendum (which is far greyer). It's what to vote for. To be even clearer regarding the unrealistic idea here imagine 80% of people were progressive no voters. In that state a no vote looks like a call for a treaty. But there aren't that many. Very generously progressive no maybe a bit above 10%. That just gets lost in the conservative no and will absolutely be used say Australia does not want a treaty.
• In no world is a voice worse than no voice. I agree with you that this sort of thing is often used to bait out a raw deal but that is not what's happening. You can kind of see it in the desperation from the conservative no. The total fabrications and language used. They do not want it because it's not a consolation prize.