Don't know for sure, but I would think they would sue Twitter. Then if they are successful Musk would go after the ex-Twitter people.
Twitter is a corporation, a limited liability corporation.
The stockholders can’t be sued. The board of directors is probably liable to a lawsuit brought by stockholders. However, Elon Musk bought them out and they were paid.
I’m not a lawyer and never played one on TV but doubt the individuals can be meaningfully sued. The whole of corporate being is the concept of limited liability of stockholders