Then he appears to have been saying the same things some Christians do, that God acted on nothing at all, and then the universe just appeared. If there’s nothing to act upon, why should God, or gravity, be able to turn it into a universe?
So if God can act on nothing and turn it into the universe, if God can “create a universe from nothing”, then it must be possible for some things to turn nothing into the universe.
But if it is possible for some things to turn nothing into the universe, why could that not be one of the powers of gravity?
It seems to me that if you find gravity creating the universe from nothing absurd, then you must find God creating the universe from nothing equally absurd. Either way, you end up with the universe being created by something acting on nothing.
Or you must start special pleading fallacies and say that God is somehow exempt from all the rules and intuitions you would bring to bear to analyze whether some proposal is rational or absurd.