Theism usually involves God as the explanation of why the world exists, and why we are conscious. In usual simulation scenarios, a world happens through physics and natural selection etc. And then a copy of part of that world is made. Yes, the copying process "made" the copy, but most explanations of how the copied world is the way it is (from the point of view of those in it) still has to do with physics, natural selection, etc. and not the copying process.

In other words, "who designed our world?" is more relevant than "who created our world?".