Doesn't quantum indeterminism (edit: quantum uncertanty) prevent that?

Any kind of quantum fluctuation, which "could" have had a makroscopic, relativistic effect must have had such an effect (f.e, in an early universe).

Either you except indeterminism or a nonlocal hidden variable - my guess is indeterminism is far more exceptable.

I always say "physical/logical" to note the known laws of physics of our universe and the logic that describes it.

If you say only "physical" - then you limit yourselve only to that which is directly observable, testable and foreseeable. And that hinders a more relaxed approach of discussing such "far-out" possibilities as required in such cases.

Point being: IMO the only valid physical/logical speculations are those that relate to the physics and logic we know of (or a variation of it in an indeterministic universe),

Only Past Eternity stays completely (or mostly) in such a physical/logical frame. Creatio Ex Nihilo is on the other hands, completely out of it with no hypothetical and (not to mention) no observational evidence offered.

It's the most unlogical thing ever conceived: no theory explains it - yet it has the "same" probability as any other option in the physically unknown.

If You "can" put the known logic and laws into the physically unknown and make it into a coherent, workable, testable theory - then any such theory is "more" probable then others without it.

Minimalism and reductionism, which are the the main reasons for allowing/prefering Creatio Ex Nihilo, break down after some scrutiny. If You talk about one singular event in all eternity (or non-existence), which just happens to be a universe capable of intelligent life - then you need to offer some theory - any kind of theory, that explains just that (and the logic of it). How can "Non-Existence" allow for any kind of Existence and why in all eternity just for 1?

If we talk multiple Creatio Ex nihilos for completely separated spatial/temporal universes, then their numbers can easilly exceed the nr. of universes that happened in a Eternal Existence.

Not just that - universes born out of Ex Nihilo would allow not just all possibilities as Eternal Existence allows for (based on known physical laws and logic) - it would also allow for universes with laws and logics completely unknown to us (illogical to us - just as Creatio Ex Nihilo is illogical to us).

So when You think about it Past Eternity is the simpler and more logical solution and as such a valid starting point for further specualtions.