The goal of evolutionists is to “explain” everything found in nature naturalistically.
That's the goal of all scientists in any field of science. Nature is what we can perceive, measure, detect, and try to understand. Anything supernatural is beyond investigation, and thus useless as a means to try and understand nature.
Claiming "we are stuck to Earth by the power of Shiva" doesn't do anything useful towards our understanding of gravity. Claiming "Thor makes fire go" does not help us in any way to understand how or what fire works. Claiming "Jawheh created all species of life" does not do anything to help us understand how life came into existence.
Furthermore, such claims cannot be proven or disproven*. "Zeus created us from his brother's excrements" is just as (in)valid and plausible as "We came into existence in Shiva's dream", which is just as plausible and (in)valid as "The Holy Trinity created us from dust"
*) of course the more ridiculous details that contradict reality in many supernatural interpretations of nature can be disproven.
This is really the “bottom line” for them (they will even go so far as to insist that science be defined as the search for “naturalistic explanations”
Indeed. If anyone could probe or even interview their god(s) of choice reliably, scientists would be happy to use that source of knowledge too. Unfortunately any and all of the thousands of gods people believe in conveniently hide themselves in the minds of their believers only. It's almost as if they don't exist.
Such a view excludes the possibility of creation a priori
No, it does not. Scientists would be happy to conclude some things or all things were created, as soon as they find evidence that it is. But such evidence simply hasn't been found yet. There's stuff we don't understand yet. There's stuff we can't explain yet. But none of that is explained by saying "Surely we exist because Shiva or Thor created us"