What do you mean? They offered refunds not because of the closures but because of Park Pass. They could've easily honored the original terms of the AP post-COVID. They chose not to. Besides, there is a ton of leeway in the current terms of the AP program that you agreed to:
For example:
Some Pass benefits and features may not be available during periods of limited capacity. Also, park experiences and offerings may be modified and are subject to limited availability or even closure.
In reality, as long as they refund APs, no one is going to even consider a lawsuit. It would be fruitless. This is a theme park membership, not an insurance contract. As I said, services change all the time and you get your money back. It's pretty straight forward.