Although the fallback was activated, strictly speaking, an emergency upgrade has not been performed. The contracts deployed on op-mainnet have not been changed from those approved in Protocol Upgrade #7: Fault Proofs. The ability for the Guardian or Deputy Guardian to switch to the permissioned fallback was built into that proposal as part of a staged, responsible rollout of fault proofs.
The safe guards, including the ability to change the respected game type are documented in the original fault proofs governance proposal, the optimism docs for fault proofs and the OP Stack specification.
If you need help with understanding how to work with these safe guards the OP Stack developer forum is a good place to ask questions. We welcome feedback to help us improve, especially if there are areas where we can increase clarity!