If the universe will never leak any information about its origins, then those origins cannot affect us in any way, ever. This doesn't make any such hypothesis less likely, but it makes them irrelevant to us.
If we are in a simulation and this simulation obeys similar constraints to our computational models, we can test hypotheses on the basis of information theory. Or possibly find error-correction codes encoded in string theory as some quantum physicists have suggested.
The universe does not owe you visibility into its origins, the lack of it does not make the hypothesis any less likely.
> If there is a concise and complete model of the universe, that is sufficient for it to exist.
Sounds like the ontological argument [1], one of the worst contortions of apologia ever imagined.
[1]: https://en.wikipedia.org/wiki/Ontological_argument