What Are the Rules of Something from Nothing?

[Tobie]

the universe was a singularity, which is definitely not nothing.

But the singularity has a cause since it didn't always exist.

The singularity is a mathematical construct, and is probably a placeholder in the theory until we can find some more evidence for what happened at and before the Big Bang. The fact that we don't know for certain doesn't mean you can use your god-of-the-gaps approach though. Science doesn't know does not imply god.