You don’t think private contracts should be enforceable in other countries? I don’t that would make for a great world to live in.
The contract should be subservient to the laws of the country/state. She may have signed it in the US. But if the non-disparagement is not legal in the UK it shouldn't be enforceable.
The contract should be subservient to the laws of the country/state. She may have signed it in the US. But if the non-disparagement is not legal in the UK it shouldn't be enforceable.