Has he said that was what he meant? Hawking authored a book entitled "God Created the Integers." I felt that meant that he believed in God who created the universe, not that he wanted something to replace God.
I've always felt that God is the Ultimate Scientist, who knows all and understands all. The closer one is to understanding as much as is humanly possible, the closer one is to understanding all, as God does (keeping in mind that the capacity of God's understanding and knowledge dwarfs the best man is capable of).
The mathematical laws and building blocks of life (i.e. DNA) that make up God's creation are so complex only God can fully understand it all, after all, He made it. The best we can do is try to understand as much as we can. The more we can figure out, the closer we are to God.
And for that matter, God is physics. God created physics. And everything else.
I got the impression that science is his G-d but I could be wrong.