To me, the simulation hypothesis definitely does not imply a supernatural creator. 'Supernatural' implies 'unconstrained by natural laws', at least to me, and I see no reason to expect that the simulation creators are free from such constraints. Sure, it means that supernatural-seeming events can in principle occur inside the simulation, and the creators need not be constrained by the laws of the simulation since they are outside of it, but I fully expect that some laws or other would govern their behaviour.