Anyone who affirms something begins to exist without a cause is on no ground at all.
But there is no more special metaphysics in the creation of an atom than there is in me sitting here, now.All of creation is creation ex nihilo, there is something special or exempt or subject to some sort of "other" causation. I don't need to know how God causes either, I can know that it happens, and that is enough for a metaphysical argument.
But it doesn't prove there is acausality, as in, something appears from literally nothing.
I don't need to prove not-acausality, that is a perfectly reasonable and safe first principle.
"that suggests atoms originally did appear out of nothing" — my understanding is that they qualify the word nothing to actually not be nothing, but vacuum energy or something like fluctuations in the quantum foam, or some such statement. Then the question becomes, where did that vacuum energy / quantum foam come from? What caused those fluctuations? Even Klauss's book "something from nothing", when read carefully, becomes "something from something".