They would either a) lie and say it anyway or b) find something else to bitch about. The conservatives oppose the voice and no amount of reason or evidence will stop them from finding an issue or making one up.
You’re not wrong, but the effectiveness of their opposition would be lessened a fair bit if Labor were smarter about their messaging.
You might be right, but when you don’t care at all about truth, you can say anything you want. Most claims they’re making can be easily fact checked, but they also rely on most people not having the time or the energy to actually read anything in detail.