You are misrepresenting the "god of the gaps" argument. According to RationalWiki: "God of the gaps (or a divine fallacy) is a logical fallacy that occurs when believers invoke Goddidit (or a variant) in order to account for some natural phenomena that science cannot (at the time of the argument) explain." The argument here is not for a particular natural phenomena, but for why there is something rather than nothing and why that something operates under a series of very precise laws. Science can explain the "what" of natural phenomena, but cannot explain the "why", or that which pre-existed the entirety of the natural universe because the scientific method cannot apply to that which cannot be observed.