I agree, the board cannot simply declare a contract void. But they are effectively taking a stance that they do not intend to honor it.
As I understand, the purpose of the newly proposed legislation is to void the contract. I’m not sure the board has to act since, by law, the contract will be void.
Since there will be a state law voiding the contract, I think this means Disney will have to initiate the lawsuit.
As you point out, Disney probably will challenge the law as unconstitutional.
Frankly, I’m just not sure since I’ve never seen anything like this before.
But at least Disney has turned this into a contract dispute, which I suspect was their strategy all along.