Does it stipulate that the billion has to be in cash? What if he trades rides to the ISS for the board members? If it doesn't have to be in cash, then it could cost Musk less than the number of the contract.??
Not sure if you're serious, but no, he can't pull crap like that and neither can anyone else who signs a contract specifying a penalty in dollars. Rides to the ISS aren't dollars.
Of course I'm not serious. If the board accepted payout equivalents for themselves and not the remaining stock holders, they would not be upholding their fiduciary duties. Oh, and then you know, accepting of bribes and what not.
A great way to spend a billion!