I read Grunbaum's article, the Pseudo-Problem of Creation in Physical Cosmology, at the infidels website. Now, I'm not an expert in cosmology, so I will focus more on Grunbaum's metaphysical critiques. I'm not really a defender of Craig's Kalam argument, however, Grunbaum's critiques were pretty weak. For example, Grunbaum attacks the famous straw man that no one defends, and he mentions "Thus the question more or less tacitly assumes some sort of temporal beginning for the physical universe, preceded temporally by a supposed state of nothingness." Craig's Kalam, does not assume a temporal beginning for the physical universe. Grunbaum doesn't even attack Craig's Hilbert's Hotel Paradox.From my point of view, Grunbaum is being sloppy because he is not very clear on what types of causality is he talking about such as efficient, final, material and formal. One can interpret the first premise, "Whatever begins to exist has a cause" in the efficient casuality sense, which doesn't presuppose physical time. Grunbaum also mentions that Aristotle's "external force is needed as the cause of a sublunar body's  nonvertical motion" principle has been refuted, but no cosmological argument assumes this principle. Rather, some of the arguments are grounded in act/potency, simplicity/composition, contingency/necessity theories. Of course, there are more specificities within those metaphysical theories that Grunbaum never touches upon, but maybe in other papers he does.