Because he signed a contract to that effect, without any contingencies if the stock went down. He doesn’t really have a choice except to go through an extended legal process that likely will end up going against him.
They can’t accept anything like that , twitter board would get sued by their shareholders for any price renegotiation.
Shareholders would sue them as most legal theory says twitter would win in court and enforce the deal, so there is no reason for the board to renegotiate instead of going to court, the board has fiduciary responsibilities.
Why not? Elon would be snarky to not buy and only lose $1B vs $10B. Clearly after investigation the company isn’t worth that and the public markets will vet forget. The stock likely tanks to < $10 over the next year now.
That model works when the parties in power own the business
The board does not own twitter, they only have fiduciary power to act on behalf the interest of shareholders. The merger agreement is strong and legal precedence in such cases has almost always been in favor of the seller , Twitter's probability of winning in court is therefore quite high and they can reasonably expect to force Musk to honor the agreement.
Given this scenario, there will be significant portion of shareholders ( likely the majority) who would want to take the legal route and try and maximize their value, even more so because now the stock is not going to reach same levels anytime soon.
If the board did not honor these expectations, those shareholders have good cause to sue and win an argument that board did not do their job[1] and have to compensate them for lost value in the sale. Loosing such a case(likely) will be catastrophic for the board members.
[1] This construct and limitations on the board is there for good reasons, otherwise a buyer would just bribe the board with far smaller amount than the value of company .
