GLT: "-That assumes a materialist point of view, that the creator would be of the same substances (matter, energy, space, time) as the things created.
not really, it assumes only that the first dimension, time, is fundamental and eternal.
The supposed creator of the multiverse would appropriately totally extend in that eternal dimension, but not moving through it,- as we do. He would always be bigger=older as his creation. no matter how big it gets. whereas the OP argues, that
a bigger creation= multiverse would shrink the creator by comparison.
Time is a dimension, what we experience is movement through time.
What really has shrunk is our ego , because we assumied we were quite significant, in the days the bible was written. We still live in the center of the universe though, but not the supposed multiverse.