Going a bit further, this could absolutely be used for a denial-of-service attack; but would otherwise be 'sandboxed', similar to how exploits for a Universal T

Going a bit further, this could absolutely be used for a denial-of-service attack; but would otherwise be 'sandboxed', similar to how exploits for a Universal Turing machine are still limited to reading/writing the machine's tape. They can't, for example, hijack an SSH session or whatever (unless there are serious vulnerabilities in the prover/turing-machine implementation)