i’m not sure i follow you. i can prove that blue cheese is my favorite, it’s all i eat. hook, line, sinker. it would be much harder to prove that blue cheese is the best, but still possible. i would look at worldwide cheese consumption and production, i might have expert cheese tasters evaluate different kinds, i could survey the population at random. it still wouldn’t conclusively prove that blue cheese is the best, because that doesn’t mean anything, but i could then say something about who likes what cheese, and maybe even why.
but if i never broached the subject, i never made a cheese claim, i wouldn’t have to prove anything. claiming there was a global flood is a claim, not claiming so does not require any evidence. the non-claim would be akin to the null hypothesis in statistics. another way to look at this would be to say that not-smoking isn’t a habit, because not-smoking is the default position.
in the same way, claiming the amount of water on earth has remained nearly constant is the default position. there are tsunamis, and depending on one’s perspective, it could appear that water had covered the entire world, but that is only a local flood.
i’m kind of digressing, because i got interested in earth’s water’s origins and looked up a bunch of stuff. but yeah… i don’t have to prove something i didn’t say.
regarding the OP, i’ve also heard that mormons wear special underwear;p that’s a little silly, but there is also the entire claim about the golden tablets that nobody ever corroborated. as they were described, they should have weighed over 150 pounds, yet they were easily moved about by just one person. it’s just another miracle;p