Could be a matter of leverage. Musk had the leverage to buy the stock at a premium, which forced investors (the board) to take the offer. So some of that leverage is likely in the form of other investors working with Musk.

Also, Musk came a long at a time when Twitter was vulnerable. They didn't see him as the threat he's become, and he also threatened to expose the company as being mostly fake - bots made up over half their traffic. So selling out seemed like the safer option.

On the other hand, the CIA pushed Twitter to the forefront, and used their leverage to install DS players, and get companies to spend their advertising $$ at Twitter. Once the company went public, that limited the CIA's ability to control Twitter. They could through their minions, but not directly. They also lost leverage as the company grew, and institutional investors got involved.