That's an interesting line of argument. Craig's Kalam argument isn't my favorite of the Cosmological arguments to work with. Not that I don't think it's good. But I think you can have a more focused discussion when you work with cosmological arguments that focus more closely on necessity vs. contingency. Craig's argument goes into a lot of detail from contemporary science that I don't think is necessary. I'm not saying that his argument doesn't work, it's just not my preferred way of addressing the issue.