The multiverse theory is just the recognition that all energy evolves from a single wave function that must always fluctuate because of its mathematical form. The fluctuations produce an infinite distribution of “fields” that continuously undergo symmetry breaking that results in an infinite distribution of forces, particles, and fields. A tiny number of these symmetries result in a set of forces, particles, and fields that don’t spontaneously collapse as they evolve from extremely high homogeneous energy states (big bang) to highly differentiated low energy states (quarks, electrons, neutrinos) needed for chemistry and biology. Most of the matter in the Universe (dark matter) is still beyond our science because we evolved at such low energy states.
Just because we don’t have “all” the natural answers at this moment in time doesn’t mean we have to accept a supernatural explanation. Supersymmetry and string theory have some pretty good models that unify gravity with QFT and account for the FSC but it will take decades or centuries to prove or disprove these models. Once thing I’m sure of. Leonard Susskind rejects any supernatural explanation and is a committed atheist.
Susskind can explain his theory to God at his judgment.
I don't see it. Anyone committed to some ideology, whatever that might be (i.e., atheist), isn't adhering to the scientific method.
Why shouldn’t we consider string “theory” and the multiverse “theory” to be supernatural answers? They certainly don’t qualify as naturalistic science.