I don't think stephen hawking is trying to lead any of us to believe that his statement was one of scientific fact, necessarily.
Also, Ray Comfort is, as usual, largely incorrect here. First, one presumes that the laws of physics exist before the creation of the universe. as to how the laws of physics got there, we have no idea, and Hawking does not presume to know. He merely states that God is not a necessity when hypothesizing as to how the universe came about. Also, the existence of a law only implies a lawgiver in the minds of creationists: it is not an objective truth.