It’s the same reason why Twitter had to agree to the sale to Elon Musk and why they had to force it. It was a terrible move overall but since Elon was buying all outstanding shares and taking it private, the board literally had no legal choice but to take it since he was offering well over market value.
It was put to an actual shareholder vote. The individual shareholders voted yes because he was overpaying. The board was fundamentally irrelevant.