I thought the actual conclusion made was: If information can travel FTL then causality would be mutable. That doesn't carry the implied premise that causality

I thought the actual conclusion made was: If information can travel FTL then causality would be mutable. That doesn't carry the implied premise that causality is immutable. I don't think that has yet been proven. In fact, if causality _is_ mutable, it might be possible to prove that it isn't even though it is. Can of worms...