My understanding is that he wrote the code for the smart contracts and open sourced it on GitHub. The contracts were compiled and deployed to the Ethereum network. There was no infrastructure/service controlled by him responsible for running the code or processing the transactions. The core contract, once deployed to Ethereum; could not be modified or deleted by anyone.

The only "infrastructure" in the traditional sense operated by him was a static website hosted somewhere online (which was eventually taken down at the request of law enforcement). The static website offered an optional interface to the Ethereum network for convenience in interacting with the deployed smart contract. The network requests from this website were made to a public Ethereum API provider specified by the end user through their own general-purpose Ethereum wallet browser extension.