Calling the universe a brute fact is a stopping point, not an explanation, but so is calling God a brute fact. Every view stops somewhere.

Correct, and every worldview must stop at something uncaused. The difference the theist argues for is that God is offered as a necessary being whose non-existence is impossible, whereas the universe looks contingent: its constants, its particle count, its very existence all seem as if they could have been otherwise. Whether that distinction holds is the debate under the next claim, on contingency, and this exhibit should not be read as if the naturalist’s stopping point were uniquely arbitrary. It is arbitrary only if the universe is contingent, which is the thing to be argued.