Voting shares and board of directors are two different mechanisms. Just because he holds 80%+ of voting shares, doesn't mean he can control who runs the company. Shareholders can make up (elect/remove) directors on the board, the board decides who can run the company (or other officials). His vote against was likely true, but if the board is 4 seats and he only has one vote, that's 25%.

A lot of this is pretty typical, but what's interesting is what happens next. He could just remove members of the board with his 80%+ control, and build a board that backs him. I assume they have investor agreements that prevent that.

Regardless of who he puts on the board, directors have legal obligations to the SEC and all shareholders. If he wants that level of control he would need to take the company private, and various investor agreements probably prevent this.