There's no reason the code can't be sandboxed, Turing-completeness is a feature not a bug (nor is undecidability a real problem), and non-deterministic behavior

There's no reason the code can't be sandboxed, Turing-completeness is a feature not a bug (nor is undecidability a real problem), and non-deterministic behavior where it's undesirable is just a potential hazard in the real world. No system can avoid it unless that system never interacts with the outside world.