Voldemort had a feeling that even if she didn’t have what was essentially a super majority in the Wizengamot, she would still push her agenda through. That she wouldn’t care about those who disagreed with her. While all that posturing about wanting to hear about others" opinions and unity seemed like a facade to his followers, he knew better. She meant every word of it. Even though that was the case, she would still have the power to push anything she liked through and ignore those she didn’t.