There is no $1B exit clause - there's just a $1B cap to damages twitter can sue for if the deal falls through. A court would have to decide to award $1B. Twitt

There is no $1B exit clause - there's just a $1B cap to damages twitter can sue for if the deal falls through. A court would have to decide to award $1B. Twitter can further sue for "specific performance" and a court could, worst case for Musk, order that the deal go through as agreed.